Do headline writers actually read the articles?

Part I

Lyme disease is accompanied by enough paranoia. Bad headlines don’t help.

A recent article on The Daily Mail is about Lyme disease and pets. It’s actually not a bad article, outlining some important issues. However, the headline shows a big disconnect between some good content in the article and a complete misunderstanding of the situation.

The title: Warning to dog owners over the ticks that can wreck lives: Many are unaware their pets can transmit potentially deadly Lyme disease to them, say vets 

To be brief, pets can’t transmit Lyme disease. Ticks that infect pets can also infect people, but that’s it.

Part II

Dr. Jason Stull (newly minted Canadian) spearheaded a commentary in the Canadian Medical Association Journal with Dr. Jason Brophy (infectious diseases physician) and myself. The article raises the issues of zoonotic diseases and pets, particularly in high risk people, and the need for physicians to have increased awareness thereof. It outlines some of the important issues, how pets and pet contact are common, what things increase the risk, the need for more information about pet-associated disease, and the need for people to take reasonable precautions to reduce the risks.

The title of the paper is important to consider: “Reducing the risk of pet-associated zoonotic infections

The paper’s attracted a lot of attention. Some good. Some not.

Many reporters have spun it towards sensationalizing the risks. Here are some examples of (bad) headlines:

  • Experts warn pets can cause illnesses, especially in immunocompromised owners
  • Your furry friend may be carrying diseases
  • Pets can make their owners sick, researchers say
  • Who let the dogs out? Pet therapy's hidden danger

...and my favourite:

  • 8 disgusting diseases you can catch from your pet

I guess those headlines are catchy, but the key point is not that your cat or dog is likely to kill you.

The key points are:

  • Physicians need to query pet contact when individuals become ill.
  • People need to think about basic routine practices to reduce the risk of disease transmission from pets, especially in high risk households.
  • We need more information about pet-associated diseases.

More accurate, but perhaps less catchy, headlines might have included:

  • Wash your hands, don’t eat poop and don’t be stupid, researchers say
  • Docs need to ask if patients have contact with animals

Antibiotics in animals: ACVIM consensus statement

Every year, the American College of Veterinary Internal Medicine (ACVIM) commissions "consensus statements" on specific topics. They’re developed by an expert panel, put up for review by ACVIM members (board certified veterinary internal medicine specialists), and published in the Journal of Veterinary Internal Medicine.

Hot off the (electronic) press is the 2015 ACVIM Consensus Statement on Therapeutic Antimicrobial Use in Animals and Antimicrobial Resistance. Assembled by an international group of experts in infectious diseases, microbiology, internal medicine and pharmacology, it’s an expansion on the highly regarded 2006 equivalent.

To download the consensus statement, click here.


Cats and peritoneal dialysis

If you’re a regular reader, you’ll note the recurring theme of "every animal (and person) is carrying multiple microbes that can harm you, given the right circumstances. Fortunately, the right circumstances don’t usually occur."

There are situations in which those risks increase, and understanding cost-benefit is a key aspect of disease prevention. Sometimes pet factors increase the risk, such as being of a certain species (e.g. most reptiles), young in age, or having an illness (e.g. diarrhea). Sometimes it’s human factors that increase the risk, such as immune status, poor animal handling practices, behavioural issues, or the impacts of diseases or medical treatments.

An example of the last one was published in a recent edition of the Canadian Journal of Infectious Diseases and Medical Microbiology (Poliquin et al 2015). It’s a review of peritoneal dialysis-associated infections caused by Pasteurella, a bacterium commonly associated with pets (especially cats). It doesn’t really tell us anything new, but it’s a reminder of the risks that are present in certain situations.

Peritoneal dialysis is a procedure used in some people with kidney failure. It involves placing a catheter into the abdomen through the body wall. Fluid is then put into the abdominal cavity through the catheter, and removed a short time later, taking with it various substances that would normally be removed by working kidneys. As opposed to hemodialysis, which removes these same substances directly from the blood, peritoneal dialysis can be done at home; however, the catheter has to be left in place and managed properly to prevent infection. Here’s where the pet risk comes in.

The Poliquin paper reviewed records of Pasteurella isolates from peritoneal fluid from patients in the the Manitoba (Canada) Renal Program from 1997-2013. They also looked at published reports of Pasteurella peritoneal dialysis-associated infections.

In total, they identified 37 cases: 33 caused by Pasteurella multocida and four caused by other Pasteurella species.

  • Affected patients had varying degrees of illness, with abdominal pain, nausea and vomiting being most common.
  • Two individuals also had bloodstream infections with P. multocida. One was very sick with a "shock-like syndrome."
  • Contact with a cat was implicated in 83% of cases.
  • Direct contact between a cat and peritoneal dialysis equipment was reported in 25 cases. Ten of these involved the cat puncturing (teeth or claws, presumably) the line or fluid bags.
  • Infections linked to a known bite or puncture of the tubing had a much quicker onset (15 hours vs 44 hours following other contacts).
  • Two people required an ICU stay.
  • The peritoneal catheter had to be removed in 11% of patients.
  • No one died.

As I said, nothing too surprising but more data to support some basic concepts:

  • There are lots of people on peritoneal dialysis living at home with cats. The incidence of this problem seems to be low. However, low incidence doesn’t help much if you’re the one with the infection. So, preventive measures are still worthwhile.
  • Pasteurella can be found in the mouth, nose and feces of most (or all) cats, so testing cats for the bacterium makes no sense. Trying to eliminate Pasteurella from its natural host would also be futile, so instead focus on keeping it out of the person’s abdomen.
  • Since direct contact was documented in most cases (and probably occurred in at least some of the other cases), keeping cats away from peritoneal dialysis catheters and all associated items is important. That should be easy to do, and is probably a key control measure.
  • Since Pasteurella is present in most or all cats, patients should practice good hygiene around their pets, especially hand hygiene. That’s particularly true before handling the peritoneal catheter site or any equipment.
  • Punctures of the tubing or other equipment should be considered a high-risk situation. Part one is keeping the cat away. Part 2 is getting medical advice when a puncture does happen, since prophylactic antibiotics might be indicated.

Image from (click for source)


Canadian companion animal Ebola guidance


While I’ve been slow posting them, Canadian guidance for management of companion animals potentially exposed to Ebola virus and for animal contacts of people potentially exposed to Ebola virus have been finalized. It was a lot of effort for something we’ll probably never use, but if we have to use them once, we’ll be very glad we went through the process. There were also benefits of getting various groups working together and thinking about the issues, so even if we don’t use them, the process was still valuable.

Part of the process also included a practice-run of certain procedures (done in collaboration with OMAFRA staff) using our dog Merlin as the "exposed" animal.  For more pictures, see the earlier W&G post or the recent University of Guelph press release.

For anyone who's curious, here they are:

Guidance for management of companion animals that have been exposed to a human with Ebola virus disease

Guidance regarding animal ownership and contact by individuals with potential Ebola virus exposure


Rabies exposure in a shelter, again


A cat at the Washington Area Humane Society was recently diagnosed with rabies, resulting in three people receiving post-exposure prophylaxis (i.e. rabies antibodies and a series of rabies vaccines). What’s quite interesting here is the fact that the cat had been in the shelter since May. So, unless the cat was exposed to rabies in the shelter (possible, but very unlikely), that means the incubation period was at least 6-7 months. That’s not unheard of, but it’s pretty long for a cat. We don’t know exactly how long the incubation period can be, except that it’s long. In humans, cases have been identified a few years after the presumed exposure. This situation shows how the 6 month quarantine that is used after exposure of unvaccinated animals is very reasonable, but still not a guarantee. It also shows how short-term isolation of animals in a shelter after arrival can’t guarantee there will be no rabies exposure (although it’s good for many other reasons).


Cat hoarding and rabies

Over 50 cats have been euthanized in Delaware, US, after rabies was diagnosed in one 4-week-old kitten.

The cats were mainly indoor cats owned by one person - a pretty classical case of cat hoarding. All were in very poor condition. There were vaccination records for 15 of them, but there was no way to figure out which record corresponded to which cat (e.g. "black cat" doesn’t help much when you have 30 black cats in the group).

Since all of the cats had to be considered unvaccinated and they were exposed to a rabid animal, that left two options: euthanasia or 6 month quarantine. The logistics and cost of a 6 month quarantine, along with the poor condition of the cats themselves (and probably concerns about finding adequate homes after quarantine) led to the decision to euthanize the group.

Sometimes, these decisions have to be made despite knowing that the true risk of rabies exposure was very low. However, that’s not the case here. There was one confirmed rabid kitten, but other kittens in the litter had already died by the time that one was tested. The others may have also had rabies. The kittens had to get rabies from something, and if they were indoor (which is probably the case here given the primarily indoor nature of this group and their age), that means the virus probably came from one of the indoor-outdoor cats or from the mother (no word on her health status), which means there were multiple potential sources of exposure for the larger group than the one kitten that tested positive.

In some ways, they got lucky here. The kitten was taken to a veterinary clinic, where it bit a technician. The clinic fortunately did things right and reported the bite, and the kitten was tested. Otherwise, this would not have been picked up and there’s a much greater chance that the owner or someone else would have been exposed, and possibly died.

Inadequate rabies vaccination of this group led to the deaths of 50 cats, expensive post-exposure treatment of a few people (the veterinary technician, an animal control officer who was also bitten, and likely the owner), and presumably a lot of time and effort investigating this.

This case, and other recent rabies diagnoses, is plotted on

More information about rabies is also available on the Worms & Germs Resources - Pets page.

2013 US rabies recap

It’s that time of year. No, not for snow (although it is snowing here at the moment). It’s time for the annual US rabies surveillance report in the Journal of the American Veterinary Medical Association (Dyer et al. Rabies surveillance in the United States during 2013).

The highlights…

  • Over 5800 rabid animals were identified in the US. 92% of those were wildlife. That’s going to be a profound underestimation since most rabid wildlife aren’t caught and tested, but it shows that rabies is still alive and well in the US.
  • Rabies was most commonly diagnosed in raccoons, followed by bats, skunks and foxes.
  • Among domestic animals, there were 247 cats, 89 dogs, 86 cattle, 31 horses/mules, 9 sheep/goats, 3 pigs, 2 llamas, and a partridge in a pear tree. (Obviously the last one’s my lame attempt at early winter humour. Birds aren’t a rabies concern).
  • Other species affected included mongooses (38; as always, just from Puerto Rico), groundhogs (37), bobcats (16), coyotes (5), deer (5), otters (3), opossums (2), wolves (2), marmots (2), a rabbit and a fisher. Most of those are fairly typical, both in terms of the species affected and the numbers. 
  • Pennsylvania had the most rabid cats, while Texas won for most rabid dogs.
  • Vaccination history was not usually available for rabid dogs and cats. None of the rabid cats had been properly vaccinated against rabies. One of the rabid dogs had been vaccinated, a 10-month-old dog that developed rabies 7 months after receiving its first dose. This one’s a bit concerning, though. By being vaccinated at 3 months of age, it would have been considered "up-to-date" on rabies vaccination and this would therefore be a vaccine failure. No vaccine is 100% effective (although rabies vaccine is considered very effective as vaccines go) and the dog having only received only one dose because of its age was probably a key factor. 
  • The dominant rabies virus variants had a typical geographic distribution (see map above).

Three people were diagnosed with rabies during the year.

  • The first was a person who died of raccoon rabies. There was no history of animal exposure, but he had received a kidney transplant 17 months earlier. The donor had been diagnosed with severe gastroenteritis, but also had some neurological abnormalities and when banked samples from the donor were tested, rabies virus was found. Three other organ recipients were then given post-exposure prophylaxis.
  • The second person was a man from Guatemala who was detained trying to enter the US. While in custody, he developed neurological disease and died. Central American canine rabies variant was identified.
  • I assume the third reported case was the organ donor from the first case, since the case was diagnosed in 2013 (even though the person died in a different year).

As per usual, there’s a little information about Canada and Mexico in the paper.

  • 116 rabid animals were identified in Canada, 88% of those being wildlife. There were also 12 cats and dogs (combined) and 2 horses.
  • In Mexico, an important finding was the fact that, for the first time since 1938, no people died of rabies. Eleven rabid dogs were identified. However, care must be taken in comparing data from different countries because of potential differences in testing (if you don’t look too hard, you don’t find).


Animal Ebola guidance documents, hot off the press

Today, guidance documents coordinated by the US Centers for Disease Control and Prevention and the American Veterinary Medical Association were released. CDC descriptions of the two documents are below. Click on the title to get the document.

Interim Guidance for Public Health Officials on Pets of Ebola Virus Disease Contacts

This document provides interim guidance based on the latest scientific evidence and recommendations from national organizations, for the management of pets, specifically dogs and cats, owned by Ebola virus disease (Ebola) contacts.
Interim Guidance for Dog or Cat Quarantine after Exposure to a Human with Confirmed Ebola Virus Disease

The intent of this interim guidance is to provide guidance for companion animals, specifically dogs and cats with exposure to a person with Ebola, based on the latest scientific evidence and recommendations from national organizations. This interim guidance describes the process for conducting a risk assessment for exposure of dogs or cats that had contact with a human with laboratory-confirmed evidence of Ebola, and it describes how to implement quarantine of dogs or cats if deemed appropriate by state and federal human and animal health officials.

Image: Scanning electron micrograph of Ebola virus particles budding from a cell. (Source: CDC Public Health Image Library #17775)

Casual cat causality

The credit (or blame) for the alliteration goes to colleague and frequent blog material supplier Dr. Stephen Page. It relates to an article in the prestigious medical journal Lancet (Kagihara et al. 2014) entitled “A fatal pasteurella empyema.”

The article describes the case of a 60-year-old man from Honolulu who was admitted to hospital in cardiac arrest. He had various health problems and had had a cough and body aches over the past four weeks, then suddenly deteriorated. He was resuscitated and fluid was found in his chest cavity. When they collected a sample of the fluid, it was full of bacteria that were subsequently identified as Pasteurella multocida. Unfortunately, he died shortly after admission.

Pasteurella multocida is a bacterium that can be found in many animal species but is classically associated with cats. It can be found in most (if not all) healthy cats, as well as in large percentages of other species such as dogs and rabbits. It’s an uncommon cause of infection in people, and is most often linked to cat bites or contact of cats with wounds or other breaks in body barriers. However, it can also be carried by people, and cats are certainly not the only source.

Here, the patient cared for several feral cats and they often slept in his bed (which to me, would make them more pets than feral cats, but that’s beside the point). The authors don’t specifically blame the cats, but it’s inferred. However, there was no investigation (for logical reasons, since it wouldn’t change anything).

Was the cat the source?

Probably, but not certainly.

Further, why the infection developed is a bigger, more interesting and more relevant question, since just being in the vicinity with a cat doesn’t mean you’re going to get an infection.

I often get asked about testing cats for Pasteurella multocida. My somewhat flippant (but still accurate) response is “Here’s the test: Does it look like a cat? If so, it’s carrying Pasteurella.” Cheap and highly accurate.

Seriously, though, it’s true. Most cats carry the bacterium so there’s no indication to test for it. If people are worried about Pasteurella infections (which is really uncalled for, since there are many greater risks in life), they should focus on good hygiene practices, bite avoidance and bite/scratch first aid, not determining whether their cat is carrying the bacterium.

Vet clinic infections...who should pay?

The following question was posed to Dr. Patty Khuly in an article she writes for the Miami Herald.

"Our cats had to go to the vet hospital last week to have their teeth cleaned. The procedures went very well and, as predicted, both were back to normal that evening. Unfortunately, two days later they both started sneezing. First Patches and then Stumpy came down with the exact same cold. Patches got better but we had to take Stumpy back to the hospital. We actually had to pay more for his cold than for the teeth cleaning! Shouldn’t the vet have gone easy on us since our cats live safely indoors and they obviously caught the cold there?"

Dr. Khuly provides a good answer that you can find here.

Here’s my take on the subject:

There are two main questions.

1) Did the cats likely get an infection at the clinic?

  • That’s hard to say. Often, it’s straightforward. In a case like this, not so much. It’s possible the cats picked up a respiratory virus in the clinic from another cat that was sick, or from a healthy carrier. However, it’s also possible (and maybe more likely) that the cats had a recurrence of an underlying infection (or one did, then spread it to the other in the household).
  • Feline herpesvirus is a common cause of upper respiratory tract disease in cats, and a large percentage of cats are infected when they are young. Herpesviruses often live dormant in the body after infections and can reactivate at any point, causing disease. Cold sores in people are caused by a human herpesvirus, and they behave this way too. Stress is a major cause of re-activation, and the stress of hospitalization, anesthesia and the procedure could easily have lead to recrudescence of herpevirus infection in these cats.

2) Did the clinic provide the required standard of care to reduce the risk of hospital-associated infection?

  • Even if the cats acquired an infection at the clinic, it’s not necessarily the clinic’s ‘fault’, particularly if the infection came from a healthy cat that was shedding a virus, unbeknownst to anyone who would look at it. Infection is an inherent risk of hospitalization, and clinics have a duty to take reasonable measures to reduce the risk of disease transmission. That’s a bit of a moving target and it’s pretty subjective, but it’s a key point here. If the cat got the infection in the clinic, was it likely because of inadequate practices, such as failure to isolate a cat with respiratory tract disease, poor hygiene practices (e.g. poor handwashing), failure to use routine infection control measures (e.g. use of protective outerwear like a lab coat) and various other basic infection control concepts? If so, then the clinic’s liable (and should pay for the infection). If not, then it’s an unfortunate event but one that’s no one’s fault.
  • We can’t prevent all infections, but we have a duty to try to prevent as many infections as possible. If the clinic had a reasonable infection control program, had this documented, and followed their policies, they’re unlikely to be liable. Beyond providing optimal patient care, this is why vet clinics need to improve infection control practices. Too often, infection control programs are very informal, undocumented and weak, creating risks to patients and staff, and creating liability risks for the clinic. It leaves the door open for someone to claim that a hospital-acquired infection occurred, and makes it hard for the clinic to convince anyone that the infection was non-preventable.

So, was it the clinic’s fault? I don’t know, and it’s hard to prove. It probably wasn’t, but only with a good infection control program could they state with confidence that they did their best to the prevent infection.

Cystic fibrosis and pet ownership

Two recent papers have raised concerns about cats in households with cystic fibrosis (CF) patients. People with CF are at high risk for a range of complications because of their condition and the treatments that are required. Some complications can be life-threatening, so there’s lots of research into factors associated with disease in people with CF.

One of the recent studies (Morrow et al. Journal of Pediatrics 2014) looked at 703 kids with CF. As is fairly consistent with the general population, 47% lived with one or more dogs and 28% with one or more cats. Dog ownership was not associated with problems, but cat owners had an increased risk of developing nasal polyps. Nasal polyps are a common problem in people with CF, thought to be caused by allergy, infection and/or chronic nasal congestion. If there’s truly a link with cats, it’s logical that allergies would play a role. When analysis combined dogs and cats, pet owners were twice as likely to report wheezing compared to non-dog/cat owners; again, likely an allergic, not infectious, issue.

Fortunately, wheezing and polyps aren’t typically severe complications. A different situation is presented in a separate case report in Pediatric Respiratory Reviews (Pabary 2014). It describes a child with CF who had difficult-to-control symptoms that were thought to be exacerbated by a cat allergy. The child only improved when the cat was removed from the household.

Does this mean that pets should be removed from households with CF patients?

No, but it means that the cost-benefit balance needs to be considered. As the Morrow et al. paper states "Prospective studies are needed to confirm these associations and the potential psychosocial benefits of cat and/or dog ownership." Figuring out whether these relationships are real (i.e. causative) and determining what the risk of these complications means for an individual person compared to the potential benefits is the key. It’s not easy, and the cost-benefit will vary between households. That’s why there needs to be conversations between patients and their families, their healthcare provider(s) and their veterinarian. The Pabary case report indicates that pet removal is sometimes required, although that’s a rare situation - pet removal/surender needs to be very carefully considered and should not be a knee-jerk reaction (as it all too often is).

Photo credit: Tracy (click image for source)

Superbugs and import control

Issues about infectious disease risks from the pretty much totally unregulated importation of dogs continue to rise, and I’m dealing with them in one way or another almost daily at the moment. I’ll stay away from the discussion of what we are and aren’t (mostly the latter) doing in Canada, since I've covered that before.

What I want to write about now is a push in New Zealand to ban entry of dogs carrying methicillin-resistant (MR) staphylococci, including MRSA and MRSP.

The push makes sense at some levels:

  • MR staph infections are a problem
  • MR staph are currently rare in pets in New Zealand
  • We can find the same strains of MR staph in animals multiple countries, suggesting they do travel from place to place
  • Prevention is better than treatment

However, it’s not that clear cut. One issue relates to the standard line “all staph are not created alike”. Methicillin-resistance is common in a wide range of staph species carried by perfectly healthy animals. Many of those species are of little to no risk to people or animals.

A related issue is how MR staph get into a dog population. There are a few main ways. One is from humans - MRSA and other MR-staph are present in people, and most MRSA in pets is human-associated. So unless there’s a parallel extermination of these bugs in humans in New Zealand (a rather unlikely scenario), there’s an ongoing risk of exposure of native dogs.

Another snag is transmission of methicillin-resistance from common resident staph species to species that cause disease. While MR-staph infections may be very rarely identified in the country, it’s very unlikely that there are no MR-staph of any sort in New Zealand. I’d wager that I could find MR-staph of various sorts in New Zealand dogs, so this risk would remain even if dogs being imported were restricted.

Feasibility and practicality are other concerns. Yes, dogs could be tested and held at the border or in a quarantine facility awaiting results, but what would be tested, and how? How the testing is performed (e.g. what samples are collected and what lab methods are used) can have a major impact on the results. We don’t actually know how to confidently declare a dog to be free of MR-staph. If I had to make a recommendation now, it would be to take swabs of the nose, throat, rectum, skin and area around the hind end (perineum), and test each swab using an enrichment culture method. Since the two main staph of concern, MRSP and MRSA, behave differently in the lab, two different approaches would be required. Further, I wouldn’t have complete confidence in one round of testing, so I would probably want that done at least twice. It's possible but it wouldn't be cheap or easy… and you still won't get me to sign anything saying this will "guarantee" that a dog is free of MR-staph.

Ultimately, trying to prevent entry of MR-staph is rather futile, and it also doesn’t address the bigger issues, such as how antibiotics are used, infection control practices and other components of veterinary care that influence the spread of MR-staph. While I applaud the fact that they’re being proactive by thinking about ways to control these bugs, and that they're paying attention to importation, import controls aren’t going to be a great tool for MR-staph control. Paying attention to judicious use of antibiotics, use of common-sense hygiene practices in households, improvement in infection control practices in veterinary hospitals, and good basic veterinary care for pets would be much more effective.

Rabies myth-busters 101: Cats and bats

Rabies is a very serious disease.  We're very lucky in Canada that in most parts of the country the prevalence of this disease is now quite low, in large part due to wildlife control and vaccination efforts.  Unfortunately that also seems to make some people quite lax when it comes to (common sense) things like vaccinating their pets and avoiding direct contact with rabies vectors such as foxes, skunks, raccoons and bats.  Here are some of the most common misconceptions (or lapses in judgement) that we encounter.

1. My cat never goes outside, so it doesn't need to be vaccinated for rabies.

FALSE.  False false false.  It seems to be very difficult to get this message across to pet owners.  Your cat may live inside, but cats can escape.  Even my own cat, who has lived indoors his entire life for more than a decade, one day suddenly decided to explore the great outdoors.  Was I ever glad he was vaccinated at that point!  Even more importantly, bats - currently the most common rabies vector in most parts of Canada - can get into your house.  This happens even in the middle of large cities, and to people who live in apartments.  If your cat is unvaccinated and happens to have contact with a bat that gets in your house, kitty could be facing a 6-month quarantine which is not easy or fun for anyone.

2. My cat had all its shots when it was a kitten, so it's protected.

FALSE.  Cats (and dogs, and ferrets) need at least TWO rounds of rabies vaccination before they are considered fully protected.  Generally they get one dose at 3 months of age (with their last set of puppy/kitten shots) - 30 days later they are considered "primarily vaccinated".  The animal then needs a booster 1 year later (regardless of the type of vaccine used) at which point it is then considered fully vaccinated for 1 to 3 years, depending on which vaccine was used.  As soon as that 1 to 3 year window expires, kitty once again faces a 6-month quarantine if it is potentially exposed to rabies, which is just what happened to a dog in North Carolina recently.

3. If I have a bat in my house, I should get rid of it as soon as possible.

MAYBE. If you see a bat fly into your house through a door or a window, you can definitely try to shoo it back out as soon as possible as long as you don't touch it (lots of people use things like tennis rackets or brooms for this, but remember you don't need to hit the bat).  If you're not comfortable with that, trap the bat under a big bowl or bucket, or in a closed room with no animals or people, and call animal control (or a friendly neighbour) to help you with it.

BUT if the bat has touched any person or if there is a chance that your cat (or dog) may have touched the bat or been playing with it do not let the bat escape.  A risk assessment needs to be performed in these cases to determine if the amount of contact with the bat could have been enough to transmit rabies virus.  If the answer is no, the bat can then be released, but if the answer is yes, then it is very important to keep the bat so it can be tested for rabies.

Have your pets vaccinated for rabies by a veterinarian on a regular basis.  Make sure they are up-to-date and that you (or your veterinarian) have the records to show it.  It is by far the best insurance for preventing rabies in your pets, and avoiding unpleasant, long and difficult quarantine periods.  It is now summer in Canada and wildlife (including bats) are active - don't wait, get your pets updated today.


Rabies confusion and clarification: Ontario

Following the Canadian Food Inspection Agency's (rather mind-boggling) abandonment of the rabies response portfolio, there's been a scramble by provinces to figure out what to do. The CFIA will still perform testing, but will not have any role in sample collection, sample shipping or investigation. I'm not sure what most provinces are doing (and based on the calls I get from people in different provinces, I'm not alone) but in Ontario, a lot of effort has been put into working out a new system. Ontario's Ministries of Health and Long-Term Care (MOHLTC) and Agriculture and Food (OMAF) have taken on different components of the void left by CFIA. A lot of work has gone into this transition, but there's still a lot of confusion (and some misinformation).

Click here for a useful summary for veterinarians on the current situation, as provided by OMAF.

Rabies three ways

Not many days go by when I don’t get a few calls about rabies. Here are a couple from yesterday that highlight some important issues.

An indoor cat tangled with a bat. The bat’s no longer around to test so this is considered a potential rabies exposure (bats being important rabies vectors, and catching and snacking on a bat being a potential way to encounter the virus). Unfortunately, the cat was not vaccinated against rabies, meaning it needs a strict 6 month quarantine, or euthanasia. A cheap and easy rabies vaccination would have significantly reduced the issue, changing that to a 45 day observation period, and greatly decreasing the risk that the cat would develop rabies. Indoor cats need to be vaccinated. Even if the cat never goes outside, rabies virus can find its way inside (and the number of indoor cats that get into fights with wildlife or hit by cars indicates that indoor cats aren’t always indoors!). I have personal experience with that.

A horse in Texas was diagnosed with rabies. Rabies is uncommon in horses but it certainly occurs. As above, rabies vaccination is cheap insurance. No vaccine guarantees protection but it’s a very effective vaccine, a fatal disease, and horses with rabies have attacked and killed people. Every horse (in or traveling to any rabies-endemic country) should be vaccinated against rabies.

Additionally, various (continuous) reports of rabies deaths in India also highlight the importance of controlling rabies at the population level, to reduce the risk of exposure by reducing the number of rabid animals.  There is also an absolutely critical need for healthcare providers to properly handle potential rabies exposures.

The Texas rabies case can be found on Worms & Germs Map (, along with some other recent cases.

Another preventable rabies death

A recent rabies death in a Russian man highlights multiple screw-ups that led to the man’s death.

A 50-year-old man in Smolino Kovvrosko, Russia was bitten by his cat at the end of February.

  • Problem #1. The cat was presumably not vaccinated against rabies. Vaccination is not 100% protective but it’s pretty likely this was an unvaccinated animal. If the cat was vaccinated, the chance of it having rabies would have been very low.

The man went to the local "medical assistant," but rabies prophylaxis was not given.

  • Problem #2. Here was the opportunity to initiate the discussion about rabies. This would involve querying the health status of the animal and quarantining it for 10 days to see if it developed signs of rabies (which would indicate the need for post-exposure treatment). These things weren't done.

A few days later, the cat started acting strangely. A local vet euthanized the cat. Rabies was not discussed.

  • Problem #3. Malpractice. Plain and simple. A cat with neurological disease needs to be considered a rabies suspect. Bite history must be queried before euthanizing an animal. If rabies testing had been performed or if rabies had been mentioned as a possibility, the man might have been treated.

At multiple time points, there were chances to identify the potential for rabies, but multiple people screwed up and the man died as a result. Rabies is virtually 100% preventable with proper post-exposure treatment, but virtually 100% fatal by the time someone develops disease.

The location of this case can be seen on the Worms & Germs Map at

Cat attack pins family in bedroom

Actually, the title of this post should be “Obese cat attacks family after being booted in the rear as a disciplinary measure. Family freaks out but wants to keep cat.”

Oh, where to start.

1) A 22 lb cat is obese and there are obviously animal care issues.

2) Kicking a cat in the rear after it objects to having its tail yanked by a baby is hardly an appropriate training measure

3) A cat that will attack with enough vehemence to make a group of adults barricade themselves and call 911 has other behaviour issues.

4) A family that thinks a cat that has a history of aggression and that made them barricade themselves in a room and call 911 is still an appropriate family pet for a household with a seven-month-old child is delusional.

While there may well be more to this story than has been reported, it seems like the baby pulled the cat’s tail, the cat objected and scratched the child, the owner kicked the cat, the cat responded, and the owners ended up locking themselves in a bedroom and calling 911 saying "I kicked the cat in the rear, and it has gone over the edge, He's trying to attack us -- he's very hostile. He's at our door; he's charging us" as the cat screeched in the background.

Yet, after all that they apparently want to keep the cat, though they "definitely want to keep [the cat] away from the baby and keep an eye on his behavior."

Does this cat pose a major risk?

It’s hard to say. Probably not in most circumstances, but it can certainly be sent over the edge and respond very aggressively, something that has apparently happened more than once.

Should this cat be in this household?

Probably not. It’s in a household with a high-risk individual (the baby). Kids sometimes inappropriately handle animals, and this cat clearly doesn’t respond well to provocation. The owners don’t seem equipped to handle this properly. The cat might be perfectly fine in a household where it’s not provoked, but it doesn’t seem like a good fit for this household.

Can anything be done to prevent further problems?

A few things need to be considered. The first is a veterinary exam to make sure there’s not a physical reason for the cat’s response (e.g. is there a problem that made a little tail pull cause severe pain?). A consultation with a veterinary behaviourist (a veterinarian that specializes in behaviour as a result of extensive specialty training - not a self-proclaimed, untrained "pet psychologist" that the owners mentioned) would then be indicated to try to identify why this happened, and how (or whether) it can be prevented in the future.

While rarely (if ever) is there a situation where there should be no pets in households, there are situations where a combination of a certain pet and certain people doesn't fit. This is probably one of those.

Raccoons in the bed

There’s been some controversy in the past regarding allowing pets to sleep in or on the bed. I don’t get too worked up about it, since I think it’s very low-risk in terms of disease transmission for most pets and households, but a variety if reasons for prohibiting this practice have been given.

I haven’t previously heard the reason: “Don’t do it because you might think you’re petting your cat when you are actually mistakenly pissing off the rabid raccoon that’s dozing beside you.”

Maybe that should be added to at list.

A Massachusetts woman learned this one the hard way. The woman was asleep one night a few weeks ago and reached over to pet what she thought was her cat.  Unbeknownst to her, the critter beside her was actually a rabid raccoon that had come into the house through a cat door. Unhappy at being disturbed (and with a less-than-functional brain from rabies), the raccoon attacked, jumping on the woman's face and biting her lip, refusing to let go. She managed to pry the creature off her face, whack it with her phone and call 911. Animal control caught the raccoon, which was subsequently euthanized and confirmed as rabid.

From a more serious standpoint, this case highlights one of the big drawbacks of having a cat door that allows entry and exit of any cat-sized animal. Keeping cats indoors is a good idea for the cat’s health, the family’s health and the wild bird population (and avoids the cat door issue entirely!).

Animal Health Laboratory Zoonotic Diseases Report


Cat bite infections (and dumb headlines)

It's a scary sounding headline: “Cat Bites Pose Risk Of Infection As 1 In 3 Patients Bitten Hospitalized; Teeth Inject Bacteria Into Joints, Tissue” and it cites a research article from the Mayo Clinic in the Journal of Hand Surgery (Babovic et al 2014).

Cat bites are nasty. The mouth of any cat harbours thousands of different bacteria and their needle-like teeth can inoculate bacteria deep into tissues. A variety of complications can occur after cat bites, and they are not something to dismiss as innocuous.

But hospitalization of 1/3 of people that are bitten? Not a chance.

Let’s see what the paper actually said:

The paper is entitled “Cat bite infections of the hand: assessment of morbidity and predictors of severe infection.” It was a review of 193 patients that were presented to one hospital with cat bite injuries to the hand.

  • Point 1: The study population is people who went to the hospital for a cat bite, not all people who were bitten.
  • Point 2: The study only looked at people bitten on the hand(s). That’s a common site to be bitten by a cat, but it’s also a high-risk site for complications because hands have lots of sensitive  and fairly superficial structures (e.g. bones, joints, tendon sheaths, nerves) that are more likely to cause problems if they get infected.

So, it’s pretty clear that 1/3 of all bites don’t result in hospitalization. In reality it's a much smaller percentage, but you really don’t want to be part of that small group, so bite avoidance and proper post-bite first aid are still very important.

Some other highlights from the paper:

  • Nineteen percent (19%) of patients were admitted to the hospital at presentation (i.e. they had to stay at least one night). A further 11% failed initial outpatient antibiotic treatment and were subsequently hospitalized.
  • Sixty-nine percent (69%) of patients were women (not sure why - could be that more women own cats, more women get bitten by their cats, or more women are likely to seek medical care if they're bitten by a cat, or a number of other reasons).
  • Risk factors for hospitalization (compared to people that presented to the hospital for a bite but did not require hospitalization) included smoking, having a compromised immune system and a bit over a tendon sheath or joint. Those are not surprising at all.
  • Signs of inflammation (e.g. redness, swelling at the site of the bite) were associated with increased risk of hospitalization. Not too surprising either.
  • The average time from bite to presentation was 27 hours. Interestingly, time from the bite to presentation was not a risk factor for complications, as this has been reported as a risk factor previously (and it makes sense that it would be). However, don’t take that as an indication that you can wait a long time to seek medical care after a high-risk bite.
  • Complications were those that are typically encountered with cat bites (and good reasons to avoid them): abscesses, tendon infection and nerve involvement.
  • Seven percent (7%) of all patients (not just the hospitalized ones) had loss of joint mobility after resolution of infection. Remember that cat bites can have long-term consequences.
  • Cultures were only available for some patients, but Pasteurella multocida was the most commonly isolated bacterium. This bacterium is a notorious bite-associated bacterium and is commonly (if not always) found in the mouths of cats.

Crappy headline but an important topic.

Cat bites are bad, and it doesn’t matter if the hospitalization rate is 30% or 0.3%, they can still result in serious problems. They can also be largely avoided through proper cat handling, understanding some basic cat behaviour and proper first aid - things every cat owner should know.

More information about cats and about cat bites can be found on the Worms & Germs Resources - Pets page.

Photo credit: Moyogo (click image for source)

"Angels' eyes"...and this is a good idea because...?

Antibiotic resistance is a big deal. Lots of people and animals die because of it every year. It costs the healthcare systems (human and veterinary) tremendous amounts of money and it’s not getting better.

It’s been clear for years that we have to do a better job of using antibiotics responsibly, in both animals and humans. It’s a complex area, and people often spend too much time complaining about the "other" side (human vs veterinary) rather than trying to address their own problems. However, there are issues with certain practices that seem so straightforward I’m amazed they're allowed to continue and that they haven't already been addressed.

One such issue is the ability to buy certain antibiotics in large volumes over the counter at feed stores in some countries (like Canada), with no veterinary involvement.

Another is the plethora of fish antibiotics you can buy all too easily in pet stores (and which often end up being used on dogs and cats).

And today’s rant is about a group of products that's ongoing use boggles my mind: tear stain prevention products like Angels' Eyes. These are over-the-counter products marketed to reduce tear staining, mostly in small, white dogs. Yes, tear staining - an entirely cosmetic problem that has absolutely no impact on health. The scary part is that products like Angels' Eyes contain tylosin, an antibiotic of the macrolide family. (How much it contains is a bit of a mystery since that information isn't even included on the label.)

Does it make any sense to treat animals for a purely cosmetic problem for long periods of time (or lifelong) with a (presumably) low dose of any antibiotic, let alone one in a drug class that includes many antibiotics that are important for treating infections in people and animals?

In some countries, irrational antibiotic use like this is banned. More countries need to follow suit.

More spillover flu cases...2 cats in Canada

A few news articles have reported infection of two cats with the H1N1 flu virus. These are the first feline cases reported in Canada, but similar cases have been reported elsewhere, so it’s reasonable to assume that there have been previous undiagnosed feline cases in Canada. Nevertheless, it’s useful information.

Unfortunately, the new reports are very minimalistic in their details - not quite "cat-flu-dead" but pretty close. Information like what clinical signs the cats had, whether there were infected people in the household first, how infection was diagnosed and how the virus strain was confirmed would be useful.

Cases like this always raise a few questions:

What’s the risk to people in the household?

  • Pretty limited. We don’t know if infected cats are able to spread the H1N1 virus (though we know that cats experimentally infected with the H5N1 flu shed enough virus that they could pose a risk).
  • Nonetheless, it’s important to consider the household disease dynamics. From where did the cat get H1N1? From a person. With what people do most cats almost exclusively have contact? People in the household. So, if the cat was infected, it was probably infected by someone in the household or someone who visited the household, both of which pose a greater risk to other people in the household than the cat.

What’s the risk to the cat population?

  • Pretty limited for a few reasons. Most cats don’t tend to have contact with that many cats outside of the household, and the flu virus is shed for a short period of time.
  • Cats are also not very susceptible to the virus, so an infected cat would have to be shedding appreciable amounts of virus, have an encounter with a susceptible cat during the short time it’s shedding virus, and then this low-likelihood scenario would have to repeat itself in order for the virus to establish itself in the cat population.

Can cats be a source of new flu viruses?

  • In the big picture, this is the main concern. Any species that can be a host for a human flu virus and other flu viruses is a concern because of the potential that infection with multiple viruses at the same time could lead to creation of a new virus - one that is still able to infect people, but is different enough that people don’t have any immunity and current vaccines don’t work (which means it could potentially make a lot of people sick very rapidly).
  • However, the risk of this scenario is exceedingly low in cats since H1N1 infection in this species is very rare, and infection of cats by other flu viruses is ever more rare.  Therefore, the odds of concurrent infection AND reassortment of the viruses AND transmission to a susceptible host that can further spread the virus is are extremely remote.



Not everyone’s that lucky.


Also, what do you do if you have pets?








From the archives...How do you disinfect a cat?

Here's another one of my favourites from the archive (largely because it didn't happen to me) that was worth re-posting (original post date 11-Oct-2009).

I was talking with a colleague the other day and somehow norovirus came up. He explained how once, his wife had viral gastroenteritis and ended up vomiting on their cat. Weirdly enough, his wife told my wife the same story (they work together). My wife got a better version of the story which included a nice image of her chasing the cat around the house in her sickened state because the cat was splattering vomit all over the place. (Yuck!)

Anyway, beyond being an entertaining story (as long as it's not you doing the puking and chasing), it raises the question: if you've turned your cat into a biohazardous (and stinky) norovirus vector, what do you do to clean it up?

Dogs and cats cannot become infected with norovirus. However, they could potentially act as a source of infection for people if their coats are contaminated with the pathogen. Usually, I think about this in the context of someone having a little contamination of their hands and subsequently touching a pet (not a vomit-soaked animal, although evidently that can happen too).

So, what should you do? I don't really know. The CDC recommends using bleach or another approved disinfectant on contaminated surfaces, but that's obviously not an option for a cat. Heating contaminated objects to 60C is another recommendation, but again, not for a live animal.

I guess giving the cat a bath would be a good start, and it would presumably greatly reduce the amount of norovirus on the coat. However, if you have viral gastroenteritis already you're probably not in much of a state to do that. Another family member that is not flat-out sick in bed could do the job. However, anyone bathing a heavily contaminated animal should wear a mask and gloves, change their clothes after, clean any surface that gets contaminated in the process with bleach or another disinfectant, and (of course) wash their hands. Unfortunately, I suspect if you had to bath a cat covered in norovirus that you would probably end up getting infected, either from the cat or the contaminated environment. Leaving the animal covered in vomit is not a good alternative either, since it would continue to contaminate the household as well as look and smell really bad. We don't know how long norovirus can survive on an animal's coat, but it's reasonable to suspect that it could survive a couple of days. Keeping the pet away from uninfected individuals for a week or so wouldn't be a bad idea.

The easiest way to handle this is to avoid vomiting on your pets.

From the archives...Why should I vaccinate Fluffy, he's an indoor cat? (aka Why I'm glad I vaccinated Finnegan, my indoor cat)

Over the past few years, I've written a lot of posts on this blog. Hopefully the odd one's been interesting and/or informative, and in the spirit of recycling (not laziness!) I'm going to re-post some that I thought were memorable or of particular interest.

The first one is actually the second post ever on this site (original post date: April 11, 2008).

Picture this. I’m driving home from the airport and get a call from my wife who’s locked in the bedroom with our kids because a bat is flying around the house. It’s not necessarily a big deal, except for the fact I thought I might have seen a bat in the house a couple days earlier, and a bat in a house with access to sleeping people = rabies exposure! [2013 addition: Not all jurisdictions consider this to be exposure now.]

I’ll save you the long but somewhat funny saga, and just say I eventually caught the bat. Our sigh of relief was short-lived, however, because it came back rabies positive. That meant we all needed rabies post-exposure prophylaxis (2 shots for Heather and I who have been vaccinated, but 6 shots for each of the kids). We also have a dog and cat, and they had to be considered exposed as well (the cat almost caught the bat). The cat, Finnegan, is an indoor cat but was vaccinated. The repercussions on the animals were much less than on us. However, if they had not been vaccinated, we would have had a problem.

Protocols for rabies exposure in non-vaccinated animals vary between jurisdictions, but long quarantines are the norm, and euthanasia often is chosen.

The take home message is if you care about yourself, your family and your pets, vaccinate your pets against rabies - even with indoor-only animals. In most places it’s the law. It’s also good sense.

Rabies exposure...the good and bad

A rabies exposure incident in New Jersey provides another example of some common good and bad points that come up in these situations.

Fifteen people from four families, along with a veterinarian, are receiving post-exposure treatment after contact with a rabid kitten. In the all-too-familiar scenario, a kitten was found in a cat colony outside a workplace and taken home by a well-intentioned individual. A couple of weeks later, the kitten became sick, ultimately showing signs of neurological disease. It was euthanized at a local veterinary clinic, and subsequently identified as rabid.

A sibling of the rabid kitten that was adopted by a different family is under a strict six month quarantine. As opposed to most rabies exposure quarantines, the odds of this kitten being infected are reasonable high, so the little critter is certainly a concern.

The good points:

The kitten was taken to a vet.

  • This may sound simplistic but it’s critical. If the kitten had died before being taken to the clinic, would testing have been performed? It’s hard to say but it’s much less likely. While people don’t tend to think about diagnostic testing after their pet has died, it’s important to consider what might have killed the animal and whether there are any risks to people that need to be evaluated.

Rabies testing was performed.

  • Again, maybe this seems straightforward but this is a critical step. The veterinarian has to identify the potential for rabies (pretty easy here) and explain the need for testing to the owner (or alternatively, get public health personnel involved to seize the carcass and mandate testing… a much messier approach).

The bad points:

Lots of people were exposed to the rabid kitten - a total of 15 people from four families.

  • That’s hard to prevent, in reality. Kittens attract attention. Whether all 15 individuals actually had contact worthy of calling them exposed to the virus itself isn’t clear. There’s no mention of anyone being bitten. However, given the sharp teeth and playful behaviour that can easily result in little bites (or saliva-contaminated scratches), it is much better to err on the side of calling someone exposed.

All 15 people went to an emergency room for treatment on a weekend.

  • That’s a waste of resources and ER time. Rabies exposure is a medical urgency, but not an emergency. Rarely do you need to get treatment started immediately, especially if it wasn’t a large bite to the head or neck. They could have waited until regular hours and gone to their physician or public health. Often, there’s poor communication and lack of understanding regarding the time frame for post-exposure treatment, which can lead to this.

The veterinarian was exposed.

  • That may have been unavoidable. However, a young, unvaccinated kitten adopted from a feral colony that has neurological disease is rabid until proven otherwise. Basic infection control practices can reduce the risk of rabies exposure. Maybe those were used and exposure still occurred; that’s possible, but it’s a reminder that prompt identification of rabies suspects and using good infection control practices is important.

HIV and pets




Here are their specific recommendations:







The preamble to the pet section includes a great statement:


…and those precautions are:












The big gun antibiotic controversy

I'm getting ready for next week's ASM/ESCMID conference on methicillin-resistant staphylococci in animals, for which I'm involved in a plenary session about critically important antibiotics in companion animals. The whole area of antibiotics and animals in complex and controversial (and made worse by political agendas, lack of evidence and confusion about different issues).

Anyway, one thing that often gets overlooked is the difference between companion animals and food animals in how antibiotics are used, what regulations are in place, and what differences should be present between species. Just discussing antibiotics "in animals" isn't adequate, because a pet dog is very different from a feedlot steer in many respects, and many of the issues around antimicrobial use are different as well.

One question that's going to be up for debate is "should antibiotics that are used in serious resistant infections in people be used in animals?"

My answer to this important question has evolved a bit over the years. It's "yes, but..."

The but is the important part.

  • As a veterinary clinician, I see the need to treat my patients (or the patients I'm providing advice on).
  • As someone who works in the field of antimicrobial resistance, I see the issues with drug use and resistance.
  • As a parent, I don't want my kids to develop a serious infection that I may have played a role in fostering.
  • As a pet owner, I understand the desire to try to save the life of a pet.

That doesn't even cover all the issues, but it shows the variety of standpoints that need to be considered.

Back to the question at hand.  As I said, my answer is yes, but with disclaimers:

  • We need to use antimicrobials only when required.
  • We need to use antimicrobials properly.
  • We need to take measures to reduce infections overall (so that less antimicrobial use is required).

At our veterinary teaching hospital, we have a restriction policy for vancomycin, an important human drug. For it to be used in an animal, the following criteria must be met:

  • The offending bacterium must be susceptible to vancomycin (duh!).
  • There must be no other reasonable antibiotic options that are likely to work.
  • There must be a reasonable chance of survival with treatment.
  • Systemic treatment of the infection is needed (i.e. it can't just be treated with local therapy).
  • The clinician must get approval from infection control (i.e. me).

That has happened twice in the past 12 years. Both cases were dogs with life-threatening abdominal infections; they were each treated with a short course of vancomycin and survived.

That's probably 10-14 days of vancomycin use per ~200 000 patients. I don't know what the comparable numbers would be for people in Guelph General Hospital down the road, but their use would be staggering compared to ours. Also, the risk of resistance with each use is presumably much higher for each human patient since they are in an environment where vancomycin resistant bugs are present (and therefore can be selected for with treatment). Vancomycin resistance is exceedingly rare in our hospital population, further decreasing the risk.

Is there some risk? Certainly. Use inevitably carries some risk.

Does our 2 / 200 000 use constitute a reasonable human health risk? I can't see how it does.

So, is antibiotic use in animals something we can just ignore? Absolutely not. It's a big problem, just like antibiotic use in people. However, just as all animal species issues aren't the same, all types of antibiotic use aren't the same.

Are there other things we can focus on to reduce resistance? Absolutely.

  • A 1% improvement (i.e. decrease) in use of fluoroquinolones in animals would probably have a dramatically greater effect on resistance in human and animal pathogens than a complete ban on vancomycin. Fluoroquuinolones are a commonly used drug class in animals that is also important in people, and one in which resistance is certainly an issue.
  • A 1% improvement (i.e. decrease) in use of of fluoroquinolones in humans would probably have an even greater effect.
  • Better infection control, preventive medicine and other practices could potentially have an even greater impact by reducing infections and therefore the need for any drug therapy, and delaying the treat-resistance-more treatment-more resistance cascade.

Some people would say that any drug that's of any relevance in humans should not be used in animals. Some veterinarians would say no one should control their prescribing practices. Like most things, I think there's a happy (and more effective and practical) middle ground. It's not the status quo, though. We need to have discussions about how to control antimicrobial use in all species, including humans, and not just pointing fingers at the other side.  We also need to discuss how to improve infection control to reduce the need for antimicrobials, and how to improve the way we use antimicrobials when they are required.  In order to have good discussions, we also need proper data (something that's still lacking).

Different opinion? Feel free to comment (or show up in Copenhagen next week).

Cat hoarding and E. coli

Cat hoarding has been in the news in the Toronto area a few times lately. Multiple incidents of serious cat hoarding have been identified in the past month, involving large numbers of cats being kept in horrible conditions. It’s not hard to see how cat hoarding can create infectious disease challenges. I can’t see how anyone could keep a large number of cats in a house without problems, even if they worked very hard to keep things under control. Add together the  issues of keeping massive numbers of cats in a confined space, no veterinary care, poor nutrition and limited hygiene, and you can see how the cats and the building would quickly become biohazardous. Add in mental health issues and hoarding of other objects (both or which are also common in such situations), and you get a house that’s a cesspool, fire hazard and no place for humane housing of any animal or person.

When cat hoarders are investigated, there are often dead cats found in or around the house. There are also often cats that end up being euthanized promptly because of severe disease. A wide range of diseases can be encountered in such cat-dense and hygiene-deficient situations. Mostly, the typical feline diseases are found, including vaccine-preventable illness and a whole range of opportunistic bacterial infections. However, these cats can be very compromised and therefore prone to rare infections as well. A recent report describes one of these unusual infections. The report (Brooks et al, Veterinary Microbiology 2013) describes extraintestinal pathogenic E. coli (ExPEC) infection in one of about 60 cats from a hoarding situation. The cat died and the bacterium was found to be the cause of pneumonia and kidney abscesses.

Is this a major concern for feline health? Not really. This is presumably a rare infection that occurred in a highly compromised cat, and not the crux of a new problem. However, it shows the wide range of diseases that can occur and, probably most importantly, that some of these infections are zoonotic: ExPEC is actually a significant human health concern, since it can cause similarly severe disease in people. It’s been previously shown that people and pets can share the same strains of ExPEC within households, and pets have been suggested as being a potential source of some human E. coli urinary tract infections (another form of ExPEC infection).

In the hoarding situation with the ExPEC-infected cat, there was concern not only for people who had contact with the cat, but a wide range of emergency responders, public health personnel and probably many other people who entered the house (since one cat with disease probably means many cats shedding the bacterium in their feces, which means lots of contamination in the hoarder’s house).

Dealing with hoarding is a complex problem because of typically weak laws, reluctance to enforce laws, mental health issues and a range of other challenges. Early identification of hoarders with proactive intervention - before the place becomes a disaster - is important, but easier said than done.

Cowpox from a cat? Not as strange as it seems.







2012 US rabies recap

It's that time of year again… time for the US annual rabies surveillance report in the Journal of the American Veterinary Medical Association (Dyer et al 2013).

Some highlights:

  • There were 6162 cases of rabies diagnosed in animals in 2012. (This is a 2.1% increase from 2011, but I don't put much stock into changes like that when the tested cases only represent a minority of the animals with rabies.)
  • The vast majority (92%) of rabid animals were wildlife, with raccoons "winning" at 32% of all animals diagnosed. They were followed by bats (27%), skunks (25%), foxes (5.5%), cats (4.2%), cattle (1.9%) and dogs (1.4%)
  • A variety of other animal species were also diagnosed as rabid, including bison, llamas, bobcats, deer, a cougar, a mink, groundhogs, opossums and beavers. That just shows how any mammal is at risk. I was surprised at the number of rabid groundhogs (42 in 10 states).
  • While dogs accounted for only 1.4% of cases (84 animals), a disproportionate number were found in Puerto Rico (18), with relatively large numbers also in Texas (16), North Carolina (9), Georgia (7) and Oklahoma (7). Presumably this relates to a combination of lower vaccination rates and a higher level of endemic rabies in the wildlife population in these areas. It appears that none of the rabid dogs were properly vaccinated against rabies, although vaccination history was not known for many.
  • Rabid cats were mainly found in areas where raccoon rabies was common. Pennsylvania had the most rabid cats (15.6%). Other commonly affected areas were Virginia, North Carolina, New Jersey and Georgia.
  • The distribution of rabies virus types was pretty much as expected. Raccoon rabies virus predominated on the east coast. Skunk rabies covered the central US, overlapping with fox rabies in the southern regions. Fox rabies was also dominant in the Nevada and Arizona area, while skunk rabies predominated in central to northern California. Fox rabies dominated in Alaska and the mongoose rabies virus strain was found in (not surprisingly) Puerto Rico.

Some Canadian data were also reported:

  • There were 142 confirmed rabies cases in animals, 84% of which were wildlife.
  • There were 18 rabid cats and dogs, 4 livestock and one person. The person was infected with rabies while abroad, in Haiti.
  • No rabid raccoons were found - something that has been the case since 2008.

And in Mexico…

  • There were 12 cases of rabies in dogs, and those involved the canine rabies virus variant which is not present in Canada or the US.

Take home messages:

  • Rabies...bad.
  • Rabies... still here (and not going away any time soon).
  • Vaccinate your animals.
  • Stay away from wildlife.

Image: Distribution of major rabies virus variants among mesocarnivore reservoirs in the United States and Puerto Rico, 2008 to 2012. (click for source: Dyer et al. J Am Vet Med Assoc 2013)

Is flushable cat litter a public health hazard?


On one hand…

  • Water is a source of Toxoplasma exposure.

On the other hand….

  • Cats rarely shed Toxoplasma. They typically do so only for a short period of time after their first exposure (usually when they're quite young), so the vast, vast majority of household cats are not shedding the parasite.

I don’t think using flushable litter constitutes a public health risk.

More information about Toxoplasma is available on the Worms & Germs Resources - Pets page, as well as in our archives.

Pets and peritoneal dialysis

I’m not a big fan of the title of a paper in the latest edition of the Canadian Journal of Infectious Diseases and Medical Microbiology…”Pets are ‘risky business’ for patients undergoing continuous ambulatory peritoneal dialysis” (Yahya et al 2013), even though it’s an interesting paper that actually takes a reasonable approach to zoonotic disease risk from pets. I get a little concerned with titles like this that might reinforce certain excessive fears  that some physicians have (usually from lack of understanding) regarding pets and zoonoses.

The paper is a case report of a 49-year-old man with kidney failure who was undergoing peritoneal dialysis at home. Peritoneal dialysis involves infusing fluid into the abdomen and then draining it, to help flush toxins out of the body. This requires an indwelling abdominal catheter that is placed through a small hole in the body wall.  Any time a tube gets stuck into the body, there’s some risk of it acting as a pathway for infectious organisms to also get in. Good management practices are essential to reduce the risk of infection in these cases, but good practices are not always used.

In this case, the person had a dog and a cat in the household. Over the course of about eight months, the man developed four different infections. One was caused by Pasteurella multocida, a bacterium that is very common in the mouths of cats. Another was caused by Enterobacter cloacae, a bacterium that is found in the intestinal tract of a variety of species, so it may or may not have been a pet-associated infection. The last two were both Capnocytophaga infections. This bacterium is ubiquitous in the mouths of dogs, and to a lesser extent cats.

How did these bacteria cause the infections?

The patient was adamant that the pets didn’t have contact with the dialysis tubing and that they were not present when he performed dialysis. However, he admitted that his hand hygiene practices weren’t always great, so presumably he contaminated his dialysis tubing with bacteria on his hands that came from the pets (either directly or from contaminated household surfaces).

Did the infections really come from the pets?

There was no testing of the pets to confirm it, but Pasteurella multocida and Capnocytophaga canimorsus are clearly pet-associated bugs, so I don’t have much doubt that pets were the source.

So, are pets risky in situations like this?

Yes, but so are lots of things. The key is whether we can effectively manage the risk.

Does the presence of pets in the house increase the risk of a person undergoing peritoneal dialysis getting an infection?

We don’t know. I’m not aware of anyone looking at this specifically. However, since people are still able to publish single case reports of pet-associated infections, it’s fair to assume that pet-associated infections in these patients are relatively rare (and therefore make interesting case reports).

Should people undergoing peritoneal dialysis at home get rid of their pets?

I can’t support that (unless no onein the household really has any affection for the pet, in which case why not eliminate the risk by finding it a new home). Infections seem to be rare and basic practices (especially good hand hygiene) can presumably reduce the risk even further.

The authors conclude with some nice, balanced recommendations. “Our data support the recommendations by Rondon-Berrios and Trevejo-Nunez (2), Weiss and Panesar (12), Pers et al (10), Schiller et al (6) and Sol et al (3) that PD patients who own pets be made aware of the need for proper hand hygiene before PD bag changes and the risk of zoonotic infection if these precautions are not taken. The need to ensure pet oral secretions do not come into contact with PD equipment and the threat of these infections should be clearly communicated to PD patients. We recommend strict hygiene guidelines be emphasized and periodically reviewed with PD patients who have pets.”


Capnocytophaga Info Sheet

We've just posted a new info sheet about Capnocytophaga.  One member of this bacterial group in particular, Capnocytophaga canimorsus, makes the news periodically because it can cause devastating infection in some individuals, like the Ottawa woman who lost three limbs after one of her own dogs accidentally bit her.  This kind of severe infection, which is also sometimes called dog bite septicemia, is actually quite rare, but people with certain risk factors such as diabetes, alcoholism, and particularly lack of a functional spleen are at much higher risk. The bacterium very commonly lives in the mouths of dogs and cats, and is considered a part of the normal oral microflora in these animals. People are therefore commonly exposed to Capnocytophaga, yet infection is rare, but because it can be so catastrophic it's important to know the facts, especially if you or someone you know may be at higher risk.

You can read more about Capnocytophaga on the new info sheet, which you can find along with all our other info sheets on the Worms & Germs Resources - Pets page. You can also read about Capnocytophaga in the posts in our archives.

All about tapeworms and Echinococcus


There is one group of tapeworms in pets that is a particular concern from a zoonotic disease perspective. These parasites belong to the genus Echinococcus. Normally these tapeworms circulate in the wildlife population, mostly in wild canids such as foxes and various prey species, but they can also affect domestic dogs (and sometimes cats) that scavenge or hunt the same prey. In most cases the pet does not become sick, but people who are exposed to the tapeworm eggs in the pet’s feces can develop slow-growing cysts known as hydatid cysts or alveolar hydatid cysts. Over time these cysts can become very large and difficult to treat. There is also now evidence that one Echinococcus species (E. multilocularis) may be spreading - in 2012 a dog in Ontario was found to be infected with the cystic form of E. multilocularis (which is unusual in itself), but the animal had no history of travel outside of the province, therefore it was most likely infected via local wildlife.

Because echinococcosis can be such a severe disease in people, we created an additional infosheet focused on just Echinococcus. Both infosheets can be found on the Worms & Germs Resources - Pets page.

Image: Dozens of Echinococcus granulosus tapeworms from the small intestine of a dog.  Although these adult tapeworms are tiny compared to some other species, this species can cause significant problems in people through the formation of hydatid cysts.  (Photo credit: Ontario Veterinary College)

Dogs aren't always the biters....

Dogs have had some bad PR lately because of some high-profile bites and bite infections in people. So, in the spirit of fairness, I’ll write about a dog as a victim of an attack… from a cat.

A paper in a recent edition of Veterinary Dermatology (Banovic et al 2013) describes necrotizing cellulitis in a dog caused by a cat scratch.

Any infection characterized as "necrotizing" is bad. Necrotizing essentially means "dying," and any time you put "dying" in front of the name of a tissue or body part, you can assume the condition is pretty high on the "badness" scale.

In this case, the dog was a three-year-old Whippet that was bitten on the chest by a neighbour’s cat. The dog developed necrotizing cellulitis due to Pasteurella multocida, a bacterium that is commonly found in the mouths of cats, and one that not uncommonly causes cat bite infections in people as well. Within 24 hours of the incident, there was redness, swelling and pain over the area of the bite. The skin lesion progressed rapidly, with death of the skin over the affected area and development of large, deep skin ulcers, similar to what can happen in people with this kind of infection. Fortunately, the dog was successfully treated with intravenous antibiotics and survived.

Why did this dog develop necrotizing disease?

The reason one infection with P. multocida becomes necrotizing while another infection with the same bacterium does not is unknown   The same is true for most cases of necrotizing fasciitis (aka flesh eating disease) in people, which is usually caused by Group A Streptococcus or by Staphylococcus aureus. While saying it's "bad luck" is highly unscientific, it’s about all we can say in most cases, since there are often no obvious factors that would predispose the affected individual to severe disease, and the bacterial strains that cause necrotizing infection are usually the same as those that cause mild disease and that are found in healthy individuals. So the "bad luck" explanation is about all we have to offer at this point.


Why Finnegan's an indoor cat


One reason for keeping Finnegan in the house is zoonotic disease prevention. I was recently giving a talk about "Pets and immunocompromised owners" at the American College of Veterinary Internal Medicine forum, and a recurring theme for reducing the risks associated with cats was keeping them inside. (Want to reduce the risk of the cat being exposed to Toxoplasma? Keep it inside. Want to reduce the risk of Salmonella exposure? Keep the cat inside...).

Another important reason is the animal's own health:

  • Cat vs car rarely ends well for the cat, and untold thousands of cats meet their ends on roads every year.
  • Cat vs cat isn’t as bad but can lead to cat bite abscesses and transmission of a few different pathogens such as feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV).
  • When outside, cats can also be exposed to various insect borne pathogens that can be of concern. This kind of risk varies between regions, with areas such as those where there are ticks carrying Cytauxzoon felis (a parasite normally carried by bobcats) perhaps being the biggest concern.

Wildlife is another concern, in two ways. Just like with cars, cat vs larger critter such as a coyote rarely ends well for the cat. From an ecological standpoint though, greater problems occur from cats killing smaller wildlife. It’s been estimated that free-roaming domestic cats kill billions (yes, Billions) of birds and small mammals every year. I won’t go into all the details here, but there’s a good article on the Canadian Cooperative Wildlife Health Centre’s website about the impact such avid feline predators can have on local ecology.

Some people would argue that cats are better off going outside. Looking back at the cats with which I grew up, a lot died early because they were allowed to go outside. It’s hard for me to justify the risk to the cat, wildlife and public health for some anthropomorphic “he’d really enjoy being outside” argument.


Death by moggy

Ok, I had to Google that one…”Moggy” not being a typical Canadian term. Apparently, it’s British slang for "cat." Anyway, the "Death by moggy” article in the UK paper The Sun is pretty basic, mentioning the death of a 59-year-old woman who would probably be considered a classic cat hoarder. She was single and slept with 15 cats in her room, and as described by the coroner “hygiene was not what it could have been due to so many animals.”

I actually don’t buy the "number of animals" excuse. Fifteen cats is a lot, but cats are pretty clean and with some effort, it’s not hard to maintain a hygienic environment. It’s a lot of litter to clean, but it can be done. If there were hygiene issues, it probably went beyond a problem of sheer cat numbers.

Regardless, the report is pretty brief but it appears that the woman died of sepsis (overwhelming bloodstream infection) that was somehow linked to the cats. There’s no mention of whether the cats were actually the source, or if it was a matter of "lots of cats…big mess…must be from the cats." However, the woman was apparently often scratched, so it makes sense that the cats could have been the source of infection or a scratch could have allowed a bacterium from the woman’s skin to cause an infection that ultimately killed her.

Bartonella from needlesticks

Something I often discuss when doing infection control talks is needlestick injuries. The contrast between the approach to needlestick injuries (and blood exposure in general) in veterinary and human medicine is pretty astounding. In humans, there are strong educational campaigns, careful reporting, testing and treatment protocols, and increasing use of "safety engineered sharps devices" like retractable or guarded needles. In veterinary medicine, getting stuck with a needle is often considered "part of the job" and "no big deal". A study we did of veterinary technicians a few years ago found that 74% of techs had suffered a needlestick injury in the past year (Weese & Faires, Canadian Veterinary Journal 2009). I’ve had many such injuries during my career, pretty much all before I started to focus on infection control, and I honestly didn’t put much though into them (beyond ”oh crap, that hurt!”).

There are some valid reasons for the differences between human and veterinary medicine when it comes to needlestick injury prevention, not the least of which is the risk of HIV and hepatitis B virus transmission. In some ways, getting people to pay attention to needlesticks in veterinary medicine is tough because we don’t have viruses such as these in our patients. Needlesticks can cause pain, significant trauma and rarely severe (including fatal) problems (e.g. from drug reactions or infections), but the vast majority are rather inconsequential. However, a line that I frequently use is: “We don’t have an analogue of HIV or hepatitis B… at the moment. New diseases continue to emerge and you never want to be the index case.”

Is this really a risk? Well, yes. Beyond some new disease that could emerge and be a serious problem, we also have new issues being identified from bugs that we’ve known about for a while. Recent concern has been expressed about transmission of Bartonella species. This is a strange group of bacteria that are commonly found in cats and dogs. Bartonella henselae is the cause of cat scratch disease, a well-known problem, but Bartonella are attracting a lot more attention these days because they are being implicated in a range of often vague human diseases. Bartonella can be found in the blood of healthy cats (and to a lesser degree dogs), raising questions about whether a needlestick could result in transmission of these bacteria to people.

Two case reports highlight these concerns.

The first one (Lin et al, Vector Borne and Zoonotic Diseases 2011) tells the story of a veterinarian who developed a fever of unknown origin and back pain. Ultimately, he was diagnosed with Bartonella henselae infection which they speculated may have been transmitted following a needlestick injury. The needlestick link is weak here though. As a veterinarian, there are lots of other opportunities to be exposed to Bartonella henselae. It’s not uncommonly present in the blood of healthy cats and the main route of exposure is through fleas. Fleas feed on the cat, pick up the bacterium, then shed it in their feces. Cat scratches are a common route of transmission as the contaminated flea feces may be driven into the body. The veterinarian in the report didn’t recall having been bitten or scratched recently, but recall bias is an issue since scratches are common and often forgotten if not severe. Flea exposure wasn’t queried. Also, the needle with which he was stuck was a clean needle that had not been used yet. It still could have been the source of infection if it acted like a scratch, driving infected flea dirt on his skin into the wound, but I don't think this report is very strong.

The second article (Oliveira et al, Journal of Veterinary Internal Medicine 2010) describes infection by a different Bartonella speces, B. vinsonii berkhoffii, also in a veterinarian. The person was taking an aspirate from a mass with a needle and syringe and was poked in the finger as the dog was struggling. Five days after the needlestick, the person was still healthy. A blood sample was taken from the person and Bartonella was not found. However, by day 34 after the incident, the veterinarian reported having had frequent headaches for the past week, fatigue and some intermittent numbness in one arm. Bartonella vinsonii berkhoffii was detected in the person’s blood at that time. There was also an increase in anti-Bartonella antibodies between the two blood samples, which supports an active infection. The bacterium was not found in the tumour aspirate, but as a dog-associated bacterium and one that is rarely identified in people, and with the timing of exposure and disease, it’s quite suggestive that the needlestick was the source.

These may just be two reports, but they may just be the tip of the iceberg, because disease caused by Bartonella infections is often vague and probably routinely gets missed. There’s also increasing evidence of wide-ranging types of infection that may be overlooked, so people (and particularly veterinary staff) need to be aware and pay attention to the potential risk.

Needlestick injuries shouldn’t be considered part of the job. There are risks, but a little common sense goes a long way.

Information sheets on both cat scratch disease and needlestick injuries (and how to avoid them) are available on the Worms & Germs Resources - Pets page. 


Hospital animal visitation in the news

The New York Times has a nice article on hospitals that allow patient's pets to visit.  This is a controversial area, with policies (when they are actually present) that range from wide-open access to complete prohibition. Like most things in life, there's a middle ground that's the most reasonable.

The positive aspects of people being allowed to have their animals come visit are pretty obvious, since people may have close bonds with their own pets and having a chance to see their pets might make a big difference to their mental state/well-being, particularly for someone who is chronically ill.

The negative aspects are less clear. We certainly know that pathogens can be transmitted from animals to people (and in the other direction too), and people in hospitals are often at higher risk of infection and complications thereof. There's a list of pathogens we worry about, but there's a serious lack of data to help determine the severity of the risk - and how to reduce it. Organized pet therapy programs are great because they are structured and there can be a lot of scrutiny and training of the pet and handler. Visits by patients' own animals are inherently less controlled, since the individual animal and handler don't undergo the same degree of assessment and training.

I get asked to review visitation guidelines frequently, and a reasonable middle-ground can usually be found. These are some snippets from the NYT article that highlight common points.

A doctor’s order allowing the family pet to visit is typically necessary...

That's a good approach, although it's not often used. This lets the doctor decide if it is reasonably safe to have the pet visit, i.e. the patient is not at a very high risk of infection. The weak link here is sometimes the doctor, because sometimes the doctor doesn't understand the risks associated with pet contact and may not identify a concern. Other times, the doctor may not understand the relatively low risk and the potential benefits, and therefore default to banning visitation without giving it much thought. I think that's less common these days but still an issue. is an attestation from a veterinarian that the animal is healthy and up to date on all its shots.

The first part is great: making sure there are no health or behavioural issues with the animal that would pose an increased risk. The second part is very common but largely represents a lack of understanding of the issues. Too often, "has he had his shots?" is the main question that's asked about the animal, despite the fact that it's largely irrelevant from a zoonotic disease standpoint. Yes, we want to make sure the pet's rabies vaccination is up-to-date, but the other core vaccines are irrelevant from a human health standpoint (although they're very important for keeping the animal healthy overall).


Standard and logical policy. Grooming might help reduce the burden of bacteria, fungi and parasites on the haircoat, as well as a lot of loose fur and dander that could otherwise contaminate the hospital environment.


Logical. Some cats do well on leashes but it's better to have a cat in a carrier when taking it through a strange area. It also helps prevent other people from coming into contact with it.


Good policy, and it protects both the patient and the animal.


This has two important components. One is that the visitation is supervised, which is great. The other is that staff are given the ability to intervene in the unlikely even that there are problems.


This is often overlooked. Roommates might be afraid or allergic, and in those situations, visitation shouldn't happen in a shared room. There might be a way to do the visit in another room, so it doesn't necessarily preclude the visit from happening. This has to be broached in advance and in a manner  that the roommate doesn't feel pressured into consenting. It's best done by having the patient's healthcare providers approach the other patient and/or the other patient's family.

There's always some risk with animal hospital visitation. That's never going to be eliminated, but a lot of common sense practices can reduce the risk to a very low level, hopefully to the point that the risk is overwhelmed by the benefits. A little structure and a lot of common sense go a long way.

Cat scratch disease info sheet

We've just posted a new info sheet about cat scratch disease (CSD), which is caused by a bacterium (Bartonella henselae) commonly carried in the bloodstream of healthy cats. Signs of CSD in people can be quite non-specific, so (as always) it's important to let your physician know if you've been bitten or scratched by a cat if you're feeling ill, so that CSD is considered. Other than proper training and handling of cats to avoid bites and scratches, the next most important component of CSD prevention is flea control. 

You can read more about CSD and B. henselae on the new info sheet, which you can find along with all our other info sheets on the Worms & Germs Resources - Pets page.  You can also read about CSD in the posts in our archives.

H3N2 dog flu, and cats and ferrets

The first true confirmed canine influenza virus (CIV) was the H3N8 canine flu that evloved from  H3N8 equine flu. That's the virus that spread to and amongst dogs in various parts of North America. The general consensus has been that only this strain should be called CIV, since it's been the only true dog-adapted influenza virus that's developed the ability to stay and circulate in the dog population.

More recently, another canine flu virus has emerged in dogs, this time a type H3N2 in Asia. H3N2 is a common human flu type, but birds are the ultimate reservoirs of all flu viruses, and based on the genetic relationship of H3N2 from dogs and birds, it's thought that this virus came to dogs from birds.

Anytime a new infectious disease is encountered, it's important to figure out who/what it can infect. When H3N8 CIV emerged, it was shown that even though it came from horses, it was no longer adapted to readily infect horses. So, knowing a virus' origin or typical infection trends can be useful but it doesn't necessarily tell you the whole story.

Cats and ferrets are susceptible to many different types of influenza viruses, and are good species to look at when figuring out if a virus can spread to other domestic animals. A study in the recent edition of Influenza and Other Respiratory Viruses (Kim et al, May 2013) looked at transmission of H3N2 CIV between dogs, cats and ferrets.

In that study, researchers infected dogs with CIV and kept them in close proximity to cats and ferrets, but without direct contact. They also infected cats and ferrets to see whether they could transmit the virus to other cats or ferrets.

Here are some highlights from the study:

  • All directly infected animals developed some degree of illness, with cats and dogs typically developing sneezing, coughing, increased respiratory effort and nasal discharge, and ferrets only developing sneezing.
  • Cats could become infected by being in proximity to both infected dogs or infected cats.
  • Ferrets didn't get infected when exposed to infected dogs.
  • Ferrets did not develop disease after exposure to an infected ferret but 2/3 developed antibodies against CIV, meaning the virus had been transmitted, but not able to cause disease.
  • Cats shed higher amounts of virus than ferrets.
  • Dogs stopped shedding the virus by day 8 after infection. That's not surprising since influenza shedding is short-term with H3N8 CIV. It shows that use of good infection control measures, particularly isolation, can be a key component of canine flu control.


  • Dogs with H3N2 CIV are potential sources of infection for cats and ferrets.
  • Cats that are exposed to the virus can get sick and be sources of infection for other animals, presumably including dogs. Cats may be another truly susceptible host for this virus.
  • Ferrets seem pretty resistant to the virus. It probably takes fairly high level exposure for them to get infected and they are less likely to be of concern for subsequent transmission.

Interspecies transmission of flu viruses, and other viruses, is obviously an issue. Most of the attention is paid to the bird-pig-human cycle, for good reason. Birds are the reservoirs of all influenza virus variants, pigs are  susceptible to both human and bird flu viruses and can act as a "mixing vessel," and humans are the species we're ultimately most concerned about. However, the potential for disease in pets and for pets to be reservoirs of influenza for people or other animals shouldn't be neglected. I've frequently had discussions with colleagues in the medical and public health fields about the need for parallel companion animal surveillance when plans are made for emerging infectious disease surveillance and response (e.g. SARS, H1N1 flu, novel coronavirus). They typically respond with general enthusiasm, but interest and application aren't the same, and actually getting plans in place to perform coordinated parallel surveillance hasn't happened. Studies like this are just one more piece in the puzzle that indicate the need for broader surveillance and consideration of pets.

New UTI test for dogs and cats...(and a great real estate deal)

Cranimals Organic Pet Supplements has launched an at-home urinary test kit for dogs and cats that lets you "Monitor and track your pets health in an accurate and economical way, avoiding costly, unnecessary trips to the vet" (while not avoiding costly, unnecessary supplements, I assume).

The test claims to diagnose urinary tract infections (UTIs) by  "detecting blood, leukocytes (AKA white blood cells) and nitrite in animal urine." Unfortunately, it cant.

  • Blood in the urine does not necessarily mean there is an infection (i.e. this is a non-specific sign). In fact, a minority of cats with blood in their urine have an infection. They are much more likely have another problem like idiopathic cystitis that needs to be treated differently than an infection.
  • Urine test strips for white blood cells are notoriously useless in animals. Maybe they have a better, more useful version, but I doubt it.  The best way to detect these cells in the urine is to look for them using a microscope.
  • Nitrite can be produced by bacteria in the urine but it has little to no diagnostic value in dogs and cats.

There's no mention about any specific evaluation of the test (i.e. they haven't checked to see if the test actually does what it's supposed to). By the look of the picture, it seems to simply be a urine dipstick in a fancy holder marked up a couple thousand percent to make money. Actually, it seems to be an inferior type of dipstick since it only tests for 3 things, two of which are useless.

Not surprisingly, the test is to be used in conjunction with their supplements (which probably explains why a supplement company decided to enter the diagnostic testing business).

The test isn't exactly cheap either: $39.95 for dogs and $49.95 for cats (the only difference to me being the cat kit comes with a bit of non-absorbent litter to put in the litterbox to collect urine, with a nice markup there too). While marketed as a way to save money on veterinary bills, think hard about what it will really do. Beyond potentially providing misleading information that could impact proper care, it will probably end up costing owners more:

  • If the test is negative and the pet has urinary tract issues, it needs to be seen by a veterinarian to find out what's going on.
  • If the test is positive, the pet needs to be seen by a veterinarian to get treated. No competent veterinarian is going to prescribe a treatment based on an at-home test like this. So, the full range of testing will be done anyway.

Ultimately, if the pet is sick, it needs to see a veterinarian. If it's not sick, there's no indication for testing like this.

If you want to know some real facts about diagnosing UTIs in dogs and cats, check out the International Society for Companion Animal Infectious Diseases Guidelines for diagnosis and management of UTIs in dogs and cats.

If you still think this test is worth the money, I've got some great oceanfront property in Saskatoon that I'll sell you (see photo). The water skiing is particularly good in January.

Hookworm info sheet

While this morning's -7C temperature and snow don't exactly make me think about sandboxes or wandering around barefoot, warmer weather will presumably occur someday and the risk of outdoor exposure to parasites will start up again.

Since nothing says summer like hookworms, here's a new info sheet all about hookworms, including information on cutaneous larva migrans. The sheet can also be found on the Worms & Germs Resources - Pets page, along with info sheets on many other topics.

Shelter euthanasia reporting...good or bad?


Potential good points

More transparency: Euthanasia rates are often considered the "dirty secret" of the shelter world. In reality, it's not the shelters' fault that animals are being euthanized. It's society's fault because of overpopulation. Shelters should be reporting these numbers (and ensuring they are accurate), not as part of a "we kill fewer than you do" competition, but to highlight the challenges, increase public awareness and to work toward improving the shelter system.

More data: The more we understand the epidemiology of adoption, euthanasia, disease and other events in shelters, the better. Knowledge helps us figure out better ways to run things.

Potential bad points

Animal welfare: Will shelters resist euthanizing sick or injured animals that would otherwise be euthanized to keep their rates lower? If an animal is very sick, will there be the temptation to let it die rather than euthanize it, if deaths are not reportable but euthanasias are?

Overpopulation in shelters: If shelters try to avoid euthanising animals because the rates are reportable, there will be more animals in the shelters - likely more than they can actually handle.  More animals in a shelter does not mean more adoptions. Overcrowding leads to many problems such as increased disease risk, deceased quality of care, decreased human contact and increased shelter operation costs.

Outbreak potential: Yet another issue related to overcrowding is when you cram in as many animals as possible (often using carriers and other temporary housing stashed anywhere there's spare space) and decrease the time you spend with each animal, you create great potential for a disease outbreak. The more animals are present, the more likely the outbreak will take hold and the harder it will be to control.

Needless transfers: Will shelters try to transfer animals that are unadoptable to areas where this law is not in effect, simply to be euthanized outside of the recording system? Beyond the humane aspects of putting the animal through the stress of a transfer for no real reason, shipping shelter animals is notoriously high risk for shipping diseases along with them.

Cherry-picking: This already happens with some shelters, but one way to keep euthanasia rates low is to refuse to admit animals that are not likely to  be adopted. Turning them away doesn't help the animal or society (and may result in more animal suffering, among other things, if the animals are simply abandoned), but it keeps euthanasia numbers low. 

Will this work?

Shelters don't euthanize for fun. They do it because there is a finite number of homes available and the number of animals coming into shelters (especially cats) is way beyond that. This bill will not magically create millions of new homes for shelter animals. So, how will it "reduce euthanasia of unwanted animals"?

A representative of a group working to reduce shelter euthanasias added "We do not believe that it is the conscious will of the people of the state of Florida to kill over 50% of the lost and homeless shelter pets each year."  It's not their conscious will but what can/will they do about it? Euthanasia numbers might help spur interest in adopting from shelters, and if so, that would be great. But the fact is that if 50% of animals in shelters are being euthanized, it's because they don't have homes.

Probably a well-intentioned but poorly thought-out approach to the pet overpopulation problem.

Rabies update






These cases have a few recurring themes:

  • Changes in animal behaviour should lead to consideration of rabies.

Expensive cat bite

When I was in general practice, I remember going into an appointment and being introduced by an owner to his cat named "Big Screen TV." Upon seeing my surprise at the name, the owner explained that the medical emergency the cat had the year before cost as much as the big screen TV he wanted, so he renamed the cat.

If that's the case, then L.A. Times columnist David Lazarus might want to call his cat "SUV." Lararus developed an infection after a cat bite that required surgery and extensive medical care. His hand was saved, at a cost of about $55 000. The article describing the ordeal it is focused on the financial aspect and the bizarre approach to hospital billing in the US, so there's not much information on the bite or the infection itself, but it's yet another example of why preventing bites and good bite care is important, regardless of how serious the bite may appear at first.

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Songbird Salmonella in Sonoma

This story's a couple of weeks old, but Sonoma County (California) residents have been warned about an outbreak of salmonellosis in songbirds. Outbreaks of salmonellosis occur occasionally in songbirds such as finches, and can result is lots of sick and dead birds. There are also risks to other species, including cats and people.

Why cats? Cats can be exposed to Salmonella from eating infected songbirds, and sick birds are typically a lot easier to catch than healthy ones.

Why people? People can be exposed to Salmonella from areas the birds have contaminated, particularly bird feeders and their vicinity. People have been advised to remove bird feeders or clean them regularly, and to promptly remove dead birds from under feeders.

  • Removing bird feeders temporarily might help keep birds (including sick birds) farther away from people. It's not going to hurt the birds since other food supplies are typically abundant.
  • Washing feeders can reduce the Salmonella burden but it could also increase the risk to people if they contaminate themselves while washing them. Certainly, people should not wash bird feeders inside the house, especially not in the kitchen sink. They should also take care to avoid contaminating their clothing and make sure they wash their hands thoroughly after finishing with the feeder.

"Songbird fever" is a colloquial name for salmonellosis in cats - a testament to the potential for feline infection. It's uncommon but can be severe, and cats can act as a bridge between sick birds and people by bringing Salmonella into the household. This is just one of many reasons why domestic cats are better off living indoors.

Cat tongue almost kills man

BMJ Case Reports has a recent paper entitled Cirrhosis, cellulitis and cats: a ‘purrfect’ combination for life-threatening spontaneous bacterial peritonitis from Pasteurella multocida” (Hey et al 2012). (I don’t think we'd be able to use a title like that in a veterinary journal, but they often get away with titles playing on the animal side in medical journals.)

The case report describes a man who had liver cirrhosis from hepatitis C infection and alcoholism. He went into hospital with a chronic infection of his leg. He’d been seen various times for this problem and various bacteria had been isolated (leading to treatment with various antibiotics). This time, he had severe swelling of his leg that went from his calf to his groin, along with significant accumulation of fluid in his abdomen. Shortly after admission, he deteriorated and became septic (he developed an overwhelming bloodstream infection) and went into liver failure. Blood samples and samples of fluid from his abdomen were tested and the bacterium Pasteurella multocida was isolated. Fortunately, he responded to aggressive treatment.

Upon subsequent investigation, they found out that the patient had a cat, and that cat "had a disturbing habit of regularly licking the serous exudate [leaking fluid] from the patient’s chronic left leg leg cellulitis." (This probably occurs much more commonly than most people think.)

Pasteurella multocida is a bacterium that’s commonly linked to cats, and it’s a frequent inhabitant of the mouth of healthy cats. The cat wasn’t tested but it’s a reasonable assumption that this infection came from the pet. The patient was given “the appropriate advice with regard to the safe cohabitation with domestic animals” but unfortunately they don’t say what that advice was.

This is just one more in a series of reports that show the importance of asking people about pet ownership and pet contact. Asking that question initially can potentially help identify zoonotic disease risks, as opposed to asking the question after the zoonotic pathogen is eventually found when they’re trying to round out the story.

The authors list some ‘learning points’. I’ve copied two important ones below.

  • Domestic animals can, under the appropriate clinical circumstances, pose a risk to an immunocompromised host, particularly if adequate hygienic practices are not adhered to.
  • Questioning regarding exposure to domestic animals should form part of the clinical history when assessing immunocompromised hosts, allowing early institution of empiric antimicrobial therapy in the appropriate clinical scenario.

They’re both good points, although I’d remove "immunocompromised." While the risk is lower in people with normal immune systems, some risk still remains and pet contact should be queried all the time.


Connecticut officials tracking possible rabies exposure

Public health personnel in Chapin, Connecticut (USA) are trying to find a woman bitten by a rabid cat. The woman was driving down South Brear Hill Road when she came across a cat. She picked the cat up from the road and told someone else who was there that the cat bit her. She then drove away, and the cat was subsequently identified as being rabid. Now a search is underway to find the woman so  she can be given post-exposure treatment.

This is clearly a high risk situation. As opposed to other public health alerts that try to find people who were in contact with a rabid animal on the off chance that they were bitten or otherwise exposed to the virus, this person was bitten and that creates a very high risk of rabies transmission.

The outcome is simple.

  • If she gets rabies, she will almost certainly die.
  • If she was exposed but gets post-exposure treatment soon (and completes the recommended course), she will almost certainly live.

It's easy to see how this could happen. The woman probably found the cat looking injured or lost on the road, and wanted to help. However, that action, and failure to recognize the risk associated with the bite, have put her life at risk.

A few general rabies reminders:

  • Avoid contact with wildlife or any animals you don't know, especially if they seem sick or otherwise abnormal.
  • If you are bitten, make sure the potential for rabies exposure is considered. The animal needs to be observed to see if it is rabid, or it needs to be tested. If the animal can't be monitored or tested, you can't rule out rabies and getting post-exposure treatment is the safest course of action.

More information about rabies can be found on the Worms & Germs Resources - Pets page.

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E coli outbreak and dog risks

I've had a few (well... more than a few) calls about potential risks to animals from the large Canadian E. coli O157 beef recall. The main concern is for dogs that are fed potentially contaminated raw meat that has been recalled, but there is also potential for exposure through cross-contamination if people in the household consumed any suspect products, and through dogs getting into garbage containing meat packaging. The other issue is whether dogs and cats can become exposed, start shedding the bacterium in their feces and subsequently infect people. Contamination of a pet's food bowl leading to human exposure is also a potential concern, especially considering the fact that as few as 10 of these E. coli bacteria can cause infection in people.

Overall, these risks are quite low. The contaminated meat is primarily a human concern. The role of E. coli O157 in disease in dogs is pretty unclear, but there's no evidence it's a significant problem. Experimentally, disease can be induced in dogs fed relatively high numbers of E. coli O157, but natural disease seems to be rare (including in dogs on beef farms where exposure is probably relatively common). I think it's reasonable to suspect that this strain of E. coli can cause disease in dogs, but it doesn't happen very often. We also don't recognize hemolytic/uremic syndrome (HUS) in dogs (the severe form of E. coli O157 infection that can cause kidney disease in people).

The risk to people from recalled meat is real. The risk to people from pets is pretty remote. Studies have not identified pet contact as a risk factor for human E. coli O157 infection. Dogs have been implicated as vectors in a limited number of specific household situations, albeit with rather weak evidence and only when focused on people and animals on beef farms.

Overall, the risks to pets and from pets are pretty limited. The main concern with the recalled meat is human disease. That being said, I wouldn't recommend people feed recalled meat to animals instead of disposing of it, since there is a possible though slight risk to both humans and animals.

NDM-1 in a cat

When bacteria containing NDM-1 (New Delhi metallobetalactamase 1) were first identified a few years ago, I talked about it during presentations as something bad that's coming our way. NDM-1 is an enzyme that gives the bacteria that possesses it resistance to a huge range of antibiotics, to the point that few or no viable treatment options are available. Given the close relationship between animals and humans, I figured it was only a matter of time before cases were identified in animals, especially household pets. A presentation by an FDA researcher at the 2012 Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) has confirmed the finding of NDM-1 in E coli from a pet cat in the US. I can't take much credit for foresight because it was pretty predictable, but it re-affirms concerns about emerging diseases and how infectious pathogens can move between people and animals.

Not much is known about this current case, since the E coli isolate was submitted for testing as part of a large ongoing surveillance study by Dr. Dawn Boothe of Auburn University. At this point, it's unclear whether the cat had been on antibiotics earlier, whether the owner had been diagnosed with the infection, whether the owner had traveled to areas where this bug was first found (e.g. India), and other relevant pieces of information remain unknown (or at least unreported).

The cat was positive for the NMD-1 E.coli on multiple samples.  The most intriguing aspect of this case is the fact that the culture samples from the cat were collected in 2008 and 2009 - at least a year before NDM-1 was first identified in the US. That's strange and concerning, and raises lots of questions about where this super-E.coli originated.

Some possible origins of the NMD-1 E.coli in this cat include:

  • The owner may have traveled to an area where the bug was present, became a carrier and spread it to his/her cat upon returning home.
  • The owner could have been infected when traveling, but it the infection may have been minor such that it didn't require medical care or a culture wasn't taken (so no one knew it was being caused by a super-bug), and subsequently the owner passed it on to the cat. (Remember that NDM-1 is a major concern because very few antibiotics are effective against it. However, the enzyme doesn't make the bacterium that carries it inherently more able to cause disease, so minor infections are possible.)
  • On ProMed, the moderator stated that he believes stowaway rodents from India or Pakistan likely carried the bug to the US and spread it amongst other rodents, with eventual exposure of the cat through catching an infected rodent. It's possible but it's a major stretch, in my opinion.
  • Perhaps the cat came from one of those endemic regions. That's pretty unlikely but there's a lot of animal movement around the world, with very little regulation, so it is possible.

We may never know how this cat got infected, but this case should be a reminder that we need to pay attention to animal populations in parallel with the human population. I keep saying it, but getting action has been difficult. People like to talk about "One Medicine," but actually getting people to practice "One Medicine" has been easier said than done.

2011 US Rabies recap





And regarding rabies in Mexico:


Guelph Humane Society reopens


Looking back on a proactive outbreak response like this one, it's always hard to say if a bad outbreak didn't develop because it wasn't going to, or because of the early aggressive response (i.e. did it get better because of what they did or despite what they did). However, if you sit back and wait (or remain in denial), you can be sure that it's much more likely that badness will develop.

Once things have settled down, people sometimes complain that an aggressive response was unnecessary because nothing bad happened, but they're often the same people that complain that not enough was done when an major outbreak occurs. An ongoing challenge in infection control is fighting complacency, since successful infection prevention and control programs sometimes lead to people forgetting about the bad things that can happen and why such programs are in place to begin with. We should applaud facilities that "suck it up" and accept the negative PR, time and financial consequences of an appropriate response in order to protect the health and welfare of the animals for which they care and all the people (employees and public) who have contact with them.

Newmarket OSPCA in the news...again

On my way to Beth's soccer practice yesterday, I heard a blurb on the radio about how Frank Klees, MPP (Member of Provincial Parliament) told the legislature that the Newmarket OSPCA was going to euthanize all their animals because of a ringworm outbreak, and that three employees had been fired because they objected to the number of euthanasias. His statement that "We have a repeat now, at the same shelter, of what took place nearly a year and a half ago" was pretty concerning, given the severity of the earlier "ringworm" debacle. Klees, the veteran PC party MPP, has been a vocal critic of the OSPCA in the past.

Later that night, I found a little more information, which was mainly centred around complaints about the number of animals being euthanized for various reasons, and a subsequent statement by the OSPCA that there was no outbreak.

Now, it appears that a protest is being planned for today (Friday), although it's not really clear to me what they are protesting. Maybe there's more to it than is being reported and an outbreak or cull is actually underway. However, in the absence of that, their protest is better directed at the state of the animal population rather than OSPCA euthanasias.

While I don't have a lot of confidence in Newmarket OSPCA management at this point, it's hard to blame the them for euthanizing a lot of animals. It's a function of supply and demand, as well as limited capacity.

North America wide, the euthanasia rate for cats entering shelters is about 50%. That's a staggering number, but it's not usually the fault of the shelter system - it's because of the massive overpopulation of cats. When twice as many cats come in as there are available homes, something has to give. You can either build new shelters every year (obviously unrealistic), pack current shelters to the ceiling with cats crammed into crates in every corner (a perfect situation for a large outbreak and hardly fair to the cats) or euthanize many and focus efforts and resources on the most adoptable animals. As much as the "no-kill" concept has market appeal, it's completely unrealistic for cats at this time because of the simple fact that millions of new cats are born every year with no hopes for a home. A small shelter can run as a no-kill shelter, but that just means that they limit their admissions and/or don't accept cats with limited adoption potential. A large shelter like Newmarket that takes whatever cats arrive will euthanize many of them, even without an outbreak going on. In fact, to do things right, a large shelter has to euthanize lots of cats to allow them to properly care for and find homes for other cats. Sad but true.

So, while euthanasia is obviously undesirable and it gets people worked up, yelling at the OSPCA doesn't do anything. They're not going to stop euthanizing cats, because they can't. Efforts are better spent helping deliver care to stray animals and preventing the cat population from expanding.

One of the most important things anyone can do to help the problem is make sure to (as Bob Barker used to say) have your pet spayed or neutered (and pass the message along to those you know as well!).

CDC resource for veterinary health and safety

The US Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health has launched a website entitled Veterinary Safety and Health. It's designed to provide occupational health and safety (including infection control) information for people in the veterinary field, as well as people in zoos, animal shelters, kennels and other animal-contact situations. It's largely designed to be a central resource to link to available information (which makes more sense than trying to re-invent the wheel), combining a range of topics from general occupational safety to veterinary-specific infection control, hospital design and related topics.  Worms & Germs Blog is included as one of the links in their resources list under Hazard Prevention and Infection Control.

Banner year for West Nile virus

After being a relatively rare problem in most regions over the past few years, West Nile virus (WNV) case numbers have boomed lately, with large outbreaks in some US states.


Forty-nine (49) confirmed or probable human cases have been reported in Ontario, the largest number in a decade. Considering we're just heading into the typical peak WNV season, it's quite concerning as the worst may be yet to come.  At this time last year, there were only 24 reported cases.

Human cases have been reported in at least four other provinces: Alberta, Manitoba, Saskatchewan and Quebec.

Two equine cases of WNV have been reported, one in Saskatchewan and one in Quebec. It's hard to have a lot of confidence in this number because of the poor surveillance and reporting for this disease in animals in Canada, given that the CFIA has largely washed their hands of dealing with it. Infection with West Nile virus has been pretty much a non-entity in most regions over the past few years, at least in terms of diagnosed cases, and it remains to be seen whether equine cases will mirror the spike in human cases this year. Typically the trends are similar each year, so the next few weeks will tell us a lot.

United States

The US is in the midst of its largest WNV outbreak ever. At least 1118 human cases have been reported so far in at least 37 states, with at least 41 deaths. Typically less than 300 cases are reported by this time of year.  Texas has experienced a huge outbreak, accounting for about half of the US cases.

There hasn't (apparently) been a surge in equine cases, with less than 100 cases of WNV reported in horses as of August 18. Whether that's because of infrequent testing, biological or geographic factors resulting in less equine exposure or vaccination of horses (remember that there is no WNV vaccine for people) isn't clear.

Concern is being raised about risks to pets, but the true risk is very limited. While WNV infections have been reported in dogs and cats, these are extremely rare and dogs and cats are failry resistant to the virus.


Often, when a new infectious disease emerges, the first year or two are the boom years, after which things settle down. That was the pattern with WNV in most areas; however, this year in on track to meet or surpass the numbers from those early years.

Why is this happening? No one knows for sure. Changing weather patterns, by chance or through the larger spectre of global warming, are probably playing a major role. Warmer temperatures let mosquitoes mature faster and allow the virus to grow quicker in the mosquitoes. Milder winters help mosquitoes survive. Any factor that fosters more mosquito numbers and growth, particularly the subset of mosquitoes that bites both birds (the reservoir of the virus) and people, can increase the risk of human and animal exposure. Changes in rainfall, wetland management, climate and human proximity to mosquito breeding sites can all play a role.

Another shelter outbreak...a different response

'Tis the season for ringworm, I guess.

The Guelph Humane Society has closed to visitors, and adoptions have been suspended in response to concerns about the potential for a ringworm outbreak. Implementing a proactive response, all animals are being tested for ringworm and all cats are being treated. While the scope of the problem isn't yet clear (and hopefully it's minimal), this type of response is the optimal approach because waiting to "see what happens" and waiting for culture results (which can take a long time) before deciding to take aggressive measures results is a much greater chance of things getting out of hand.

In an outbreak like this, the first week or so is critical. Introduction of an animal that's carrying ringworm is hard to prevent, as is limited transmission within a shelter (even with good routine infection control practices) from that first case. That's the non-preventable component of shelter diseases. However, it's the 2nd generation of transmission (transmission of ringworm from that initial animal or group of animals to the broader population) that leads to things getting out of control. That's the preventable fraction of infections, on which we can have the biggest impact. It's during this early phase where intervention is critical  It's always better to have an overly aggressive response and simply tone it down after a few days, than to have an inadequate response that lets things spiral out of control.

More information about ringworm can be found on the Worms & Germs Resources - Pets page.

KW shelter ringworm outbreak continues

As expected, the KW humane society ringworm outbreak has gone from "we'll be open in a couple days" to "it may take months to clear it up."

The scope of the outbreak isn't really clear from press reports, but "a couple" of other animals now have signs of the skin disease. Investigation of the timing and likely sources of exposure of new cases is crucial. They may just be animals that were infected early, before the problem was recognized (the best case scenario) but investigating these "new" cases is very important because if these animals were exposed after the outbreak was identified, then there are problems with containment.

Shelter personnel have declared that they aren't planning on euthanizing more animals, but the shelter remains closed for adoptions. Stray animals will continue to be accepted. This creates a tricky situation where new animals (e.g. fuel for the fire, if things aren't under control) come in and can actually propagate the outbreak. It also creates overcrowding issues since the shelter was probably pretty full to start with, and continuing admissions with no adoptions can't be maintained for long. The shelter is looking at renting units in which to put animals - this is a relatively common approach for creating more contained spaces, and one that can be useful if good infection control practices are in place (although I've seen too many outbreaks where the offending pathogen quickly makes its way into the new units). Clear policies, sound training, careful supervision, exquisite planning and good communication are critical for making a situation like that work.

While the shelter has gone from an unrealistically optimistic time frame to a warning about long-term efforts, as with most things in life, the middle ground is usually the most accurate. Ringworm outbreaks can't be declared over in a few days (it's possible to contain it in a short period of time, but not declare an outbreak over). A few days isn't even enough time to get culture results back to figure out exactly what's happening. Testing, isolation, cohorting, mass treatment, evaluation of training, evaluation of infection control practices, and similar measures are needed, but if done right, an outbreak can be contained in a reasonably short period of time. Given the need to repeatedly treat all animals (affected animals are being bathed every three days with a medicated solution) and the time lag for ringworm culture, it's going to take at least a few weeks, but let's hope this outbreak ultimately gets measured in weeks rather than months.

KW Humane Society outbreak update

The latest info on the ringworm outbreak at the KW Human society come from the Waterloo Record (unfortunately there's still no information on the Humane Society's own website...).


Samples were collected for testing, but they decided to euthanize the 4 animals.

"You’re kind of under the gun to decide what you want to do,” said their operations manager. I can certainly empathize. It's not easy to deal with an outbreak. However, from my standpoint, if you feel like you're under the gun in that kind of situation, you're likely to make (or to have already made) mistakes. If you're managing the situation well, getting advice and following standard practices, you may be stressed, exhausted, humbled and concerned, but you shouldn't feel "under the gun." Maybe euthanasia was warranted here, but with a small number of infected animals, the ability to potentially isolate and treat them, and lots of information about how to manage ringworm to avoid further spread, it's important to avoid a panic response that leads to premature euthanasia decisions.

The three cats that were euthanized apparently did not have ringworm, but the shelter is "certain" (not sure how) that the dog had ringworm. Sudden onset of skin lesions in dogs and cats at the same time is certainly suggestive of ringworm, and if the dog was truly infected, it's hard to believe the cats were not (especially since cats are most often affected in ringworm outbreaks compared to dogs). So I wouldn't be too quick to rule out ringworm in the cats. Ringworm culture can take a couple of weeks, so it's not clear to me whether this interpretation is based on culture results or not. 

"With the results being better than expected, the humane society will not have to move larger numbers of possibly infected animals to a different facility — the usual procedure in an outbreak." While I can't say too much from a distance, I can say that moving animals to another facility is certainly not a typical outbreak response measure. It's an effective outbreak propagation measure, since it can easily disseminate ringworm to other places, so it's good to hear that they are not planning on moving animals. It's much better to manage things well at one site than to have to manage things at multiple sites.

They state that "the situation now appears to be under control." Hopefully that's true, but it's way too early to say. You can't declare an outbreak over a few days after you declare that it started. There hasn't even been enough time for any animal or environmental ringworm culture results to come back. Closing, testing, treating all exposed animals and thorough cleaning and disinfecting of the environment can be a great start, but trying to say "we won" too early often leads to inadequate response and continuation of the outbreak.

"We’re keeping our fingers crossed and hoping that everything comes back negative so we can be open for business sometime next week" Again, I'm not involved and I'm working with sparse information, but this seems to be way too early to reopen the shelter. You need to make sure things are really under control before you get out of "outbreak mode" and before you can be "open for business" again. That's especially true with a disease like ringworm that is highly transmissible and can be spread to people. Too often, a small outbreak is identified and declared over prematurely, only to be followed by a big mess in short order. Let's hope that's not the case here.

Image: Photo of a dermatophyte-positive culture specimen, which can take two weeks or longer to grow.

Local shelter ringworm outbreak

A short distance down the road from here, the Kitchener-Waterloo Humane Society has been quarantined because of an apparent ringworm outbreak. There's no information on the facility's website and information in the press has been pretty vague (both concerning aspects), but it sounds like a ringworm outbreak. Adoptions have been ceased and the Humane Society will apparently "reassess its safety protocols by the end of the week.The outbreak appears to have been going on since at least last week, so hopefully they're getting on this and have a strong outbreak investigation and control plan in place.

I haven't been involved in this outbreak so I know nothing more than what is in the press, but ringworm can be a big problem in shelters. It's a controllable disease, but the situation can get completely screwed up with a poor outbreak response. It's also sometimes an overblown problem (or not a true problem at all) in some situations, so it's critical that the outbreak is properly investigated and managed. That's not always the case, and the consequences can be serious.

There are a lot of factors that go into good outbreak management that are hopefully being done at the KW Humane Society. These include:

  • Good communication both internally and externally.
  • Transparency.
  • Sound containment practices.
  • Getting good advice.
  • Actually listening to the good advice (and not bad advice).
  • Taking the time to do it right.
  • Ensuring one is acting on correct information.
  • Spending money where it needs to be spent, be it testing, treatment, personnel or other factors. Trying to save money during an outbreak response often ends up costing much more in the end.

The independent report of the 2010 ringworm debacle at the Newmarket OSPCA should be important reading for any shelter trying to figure out what to do, and what not to do.

Rabies virus survival

I've had a run on questions about survival of rabies virus outside the body. The topic comes up periodically with respect to touching roadkill or veterinary clinic personnel working with animals that have been attacked by an unknown animal. The case of three people who developed rabies after taking care of a sheep that had been attacked by a rabid animal, probably through contact with saliva from the rabid animal on the sheep's coat coming into contact with broken skin on their hands, shows the potential risk. An important part of assessing the risk is understanding how long the virus lives outside the body.

Some viruses are very hardy and can live for weeks or even years outside the body. Parvovirus and norovirus are classic examples of this type. Some viruses, like HIV, die very quickly in the environment. Part of this relates to whether they are "enveloped" or "non-enveloped" viruses. Enveloped viruses have a coating that is susceptible to damage from environmental effects, disinfectants and other challenges. Damaging this coating kills the virus. Non-enveloped viruses don't have that susceptible coating and that is in part why they are so much hardier.

Fortunately, rabies is an enveloped virus, and it doesn't like being outside of a mammal's body. Data on rabies virus survival are pretty limited, since it's not an easy thing to assess.  To look at rabies virus survival, you have to grow the virus, expose it to different environmental conditions, then see if it's still able to infect a mammal or a tissue culture. We can do this easily with bacteria, but growing viruses is more work, especially a dangerous virus such as rabies virus.

I can only find one study that has looked at rabies virus survival (and I can only read the abstract since the rest of the paper is in Czech). The study (Matouch et al, Vet Med (Praha) 1987) involved testing of rabies virus from the salivary gland of a naturally infected fox. They exposed the virus to different conditions and used two methods to look at the infectivity of the virus.

  • When the virus was spread in a thin layer onto surfaces like glass, metal or leaves, the longest survival was 144 hours at 5 degrees C (that's ~ 41F).
  • At 30C (86F), the virus didn't last long, being inactivated within 1.5h with exposure to sunlight and 20h without sunlight.

So, rabies virus can survive for a while outside the body. Temperature, humidity, sunlight exposure and surface type all probably play important roles, but in any particular situation you can never make a very accurate prediction of the virus's survival beyond "it will survive for a while, but not very long."

From a practical standpoint, it just reinforces some common themes:

  • People should avoid contact with dead or injured animals.
  • Veterinary personnel or pet owners dealing with a pet that has been attacked by another animal should wear gloves, wash their hands and take particular care if they have damaged skin.
  • People who are at higher than normal risk of being exposed to potentially rabies-contaminated surfaces should be vaccinated against rabies.

Image: Schematic diagram of a rabies virus showing the outer viral envelope (source: CDC Public Health Image Library)

"Human suicide parasite" in cats

I love my cats. But sometimes when Bonnie and Clyde are living up to their names, puking up hair balls twice a day, peeing on the guest bed (yes, contrary to popular belief even vets can't stop their own cats from doing this sometimes), caterwauling at 3 AM, or begging for food all afternoon, they do make me c-r-a-z-y crazy - but they're not making me suicidal.

In yet another example of how the media will present study results in the manner that will sell the most newspapers or magazines, rather than the way that helps people interpret the results in a logical manner, comes an article entitled "Is Your Cat Hosting a Human Suicide Parasite?" The article talks about a study recently published in the Archives of General Psychiatry (Pedersen et al. 2012) which looked at a cohort of 45 788 women in Denmark who gave birth between 1992-1995, and found a statistically significant association between self-directed violence (including suicide attempts) in these women and their antibody titre to Toxoplasma gondii at the time of birth.  The risk in seropositive women was 1.53 times greater than the risk in seronegative women.

Toxoplasma gondii is a parasite that is shed in the feces of cats, which are the parasites definitive host.  Most house cats only ever shed significant amounts of the parasite the first time they're exposed to the parasite (typically when they're young).  Depending on where people live and various cultural practices, transmission of the parasite from scooping out litterboxes may actually be relatively uncommon compared to other possible sources including exposure from soil (e.g. working in the garden and then not washing one's hands), eating unwashed vegetables, or eating some types of undercooked meat.

The most glaring limitation of the Pedersen study is that they didn't control for any other factors that may have resulted in the women who committed acts of self-directed violence being more likely to be seropositive for Toxoplasma than others.  For example, women with mental illness may be less likely to practice good hand hygiene (one of the most important factors for reducing the risk of parasite transmission), and therefore more likely to be exposed to Toxoplasma, or there may be other factors about their health or their lifestyle that make them more prone to infection. The point is the authors only found an association in a specific subset of the population (Danish women who had given birth to at least on child).  This does not mean that the relationship is causative - they can't say that Toxoplasma infection makes people more prone to self-directed violence, only that women - in this particular group - who were seropositive for the parasite were also at increased risk for this kind of behaviour.  It's a somewhat subtle but very important difference.  The authors of the study clearly acknowledge the limitations of their work, but the news article does not do quite as good a job of pointing this out, until right at the very end where it does finally get mentioned.

Does Toxoplasma infection cause behavioural changes in rats that may make them more likely to wander into a cat's territory and be eaten?  According to an experimental study it can, and it does make a certain amount of ecological sense that the parasite could have an effect on its intermediate host (the rat) that makes it more likely to be able to continue its life cycle (via being eaten by a cat) by reducing fear in the rat. Could infection of the brain in humans cause subtle behavioural changes?  I can't deny the possibility, but humans are not rats and I would be very wary of extrapolating results from one species to the other. But is this parasite likely to "drive our brains off the highway" as the news article says?  I'm not ready to buy that, certainly not based on this study.  As the authors clearly state in the first line of the paper "Suicide is a tragic multifactorial outcome of mental illness, with complex biopsychosocial underpinning..."  There are so many things that contribute to such an unfortunate outcome that a lot more work is needed before anyone can justifiably blame a "suicide parasite" in cats.

Whether you believe Toxoplasma infection can result in behavioural changes in people or not, there are some very simple steps everyone can take to help decrease the risk of becoming infected with this parasite regardless.  These are particularly important for individuals who are immunosuppressed and women who are pregnant, because it is very well established that toxoplasmosis in these high-risk individuals certainly can have severe repercusions to either the individual or the unborn fetus.  However, it is by no means necessary for such individuals to get rid of their cats if they take these simple precautions:

  • Clean your cat’s litter box every day. The oocysts shed in cat feces usually take about 24 hours to become infective once they’ve been passed, so daily cleaning helps remove them before they reach this stage.
  • Always wash your hands with soap and water after cleaning your cat’s litter box, after working in the garden or in any soil, and after handling raw meat.
  • Keep your cat indoors. Outdoor cats are more likely to be exposed to Toxoplasma and shed oocysts in their stool. 
  • Keep sandboxes covered so outdoor cats don’t contaminate them with stool.
  • Cook all meat, especially pork, lamb, mutton and wild game, to an internal temperature of 67ºC/153ºF or higher.

More information about Toxoplasma can be found on the info sheet on the Worms & Germs Resources page.

Pet travel misinformation





  • Incorrect tapeworm treatment information.
  • No mention of rabies titre testing.








Plague from pet cat

Plague cases tend to get a lot of press. The fact that this disease killed a large percentage of the human population in a few different pandemics (albeit centuries ago for the most part) probably plays a role in that. Despite the impression by some that it's just a historical disease, plague is alive and well in certain parts of the world, including parts of the US, and infects a few thousand people every year.

Plague is caused by the bacterium Yersinia pestis, which lives in various wild rodents and is circulated by fleas. Transmission to people historically has been via fleas that jump from rats to people. However, plague isn't just a rat-human disease, as it can infect other animal species. Among domestic animals, cats seem to be most commonly infected, probably because of exposure while hunting.

The problem with plague and pets has been shown once again a case of plague in an Oregon man who likely picked up the infection from his cat. (Oregon is outside of the main range of plague in the US, where the disease is most common in the southwest). The man was bitten by the cat while retrieving a dried, decayed mouse carcass from its mouth. He developed septicemic plague (infection of the bloodstream), and then pneumonic plague (infection of the lungs), which is the worst case scenario. At last report, he was in critical condition and the prognosis for survival is probably guarded.

There's no mention of the cat's health. Most cases of cat-human plague occur in people taking care of sick cats (especially veterinarians). If a person is infected by a cat bite, I would expect the cat to have been sick with plague, although transmission has been reported from apparently healthy cats. Some other possible routes may need to be considered. If the cat in this case was exposed to plague, then plague's obviously in wildlife in the area, so you have to consider that the infected man might have been bitten by an infected flea (that came directly from an infected wild animal or that the cat tracked in) or from direct contact with wildlife, especially if his house had a rodent infestation.

Regardless, it's important for people in plague-endemic (and neighbouring) areas to be aware of plague and take measures to reduce the risk of exposure for themselves and their pets, such as:

  • Avoid contact with wild rodents (and wildlife in general, since larger wildlife species can also be infected).
  • Keep cats inside.
  • Don't let pets with outdoor access roam unobserved, where they might be more likely to encounter wildlife.
  • Have a flea control program for pets.
  • Address any animal/household flea infestations promptly and aggressively.
  • Make sure sick pets get prompt and appropriate medical attention, since diagnosing plague in a pet may be a critical factor in prompt treatment of people infected by the pet. Plague is an example of a disease for which diagnosing infection in the pet might save the owner's life.

Physicians, vets and zoonotic diseases

People like to talk about "one medicine" a lot. It refers to the concept that we're all animals, and that human and veterinary medicine should be one big happy family of healthcare providers that maintain the health of the entire family, human and non-human. I get a bit jaded talking about one medicine because there's a lot of talk but it's hard to get a lot of action. One problem is that while some people in both human and veterinary medicine are strong supporters of the one medicine concept, it doesn't always filter down to the ground level.

A study in the latest edition of the Journal of the American Veterinary Medical Association (Hill et al. 2012) presents some concerning but not surprising information about "Tennessee veterinarian and physician attitudes, knowledge and practices regarding zoonoses prevention among animal owners with HIV infection or AIDS."

The study consisted of a survey sent to 454 vets and 1737 physicians in Tennessee. Response was pretty poor (a common problem with surveys), with only 43% of vets and 15% of physicians completing it. You have to wonder why the physician rate was so low.  One potential issue is that the topic is not even on the radar of most physicians so they didn't bother to respond. If that's the case, then the people who responded could be more interested than average, potentially biasing the results (meaning that the problems described below are actually underestimated).

Here are some highlights from the study:

73% of veterinarians, but only 50% of MDs, said that veterinarians should always or almost always be involved in advising clients with HIV/AIDS about zoonotic disease risks.

  • Considering a large percentage of physicians don't initiate the discussion and don't get any additional education in zoonotic diseases (see below), I'm not sure what the other 50% of physicians think should be happening in terms of zoonotic disease counseling.

58% of veterinarians had zoonotic disease educational materials available in their clinics compared to only 3.5% of MDs.

  • Not surprising at all. Actually, the fact that some MDs have info in their offices is a bit of a surprise.

Only 5% of MDs had any continuing education (CE) on zoonotic diseases in the past three years, compared to 29% of veterinarians.

  • Pretty pathetic numbers all around. Veterinarians probably have easier access to this kind of CE since zoonotic disease topics are commonly presented at veterinary conferences, although attendance tends to be limited (as evidenced here). It would be nice to know why almost no MDs have had CE on zoonotic diseases. Is it lack of interest? Is it lack of availability? These are two completely different issues that can be addressed differently.

Almost 70% of veterinarians reported regularly talking to pet owners about the risk of zoonotic diseases in people with compromised immune systems.

  • One problem here is knowing with whom to have the talk. Asking people their medical history isn't (logically) part of the normal pet examination process, and while it's good information to have, veterinarians aren't going to cross that line and routinely ask those types of questions. That raises the question about how to initiate the discussion, and a crucial factor is having pet owners who are willing to bring up the subject. For that to happen, they need to realize that it's relevant, that the veterinarian knows something about the topic and can help, and that all information will be treated confidentially. Therefore, client education is key.

51% of physicians said they never see zoonotic infections in HIV/AIDS patients, while 44% said they almost never see them.

  • In part, that's a testament to the effectiveness of highly active anti-retroviral therapy (HAART), which has had a tremendous impact on management of patients with HIV. However, it also may be an indication that MDs don't recognize some infections as zoonotic. Certainly, a patient with Salmonella would (hopefully) result in some thought about zoonotic transmission, but there are a range of other pathogens where the zoonotic risks are less clear or less well known. When you consider that 71% of MDs never or almost never ask HIV/AIDS patients about pet ownership and animal contact, you can see how discussion and consideration of zoonoses might be poor.

Only 26% of veterinarians and 33% of MDs were able to correctly identify zoonotic pathogens of greatest concern to people with HIV/AIDS.

  • Pretty concerning numbers (especially among MDs, who do the diagnosing).

100% of MDs never or rarely contacted vets about zoonoses, and 97% of veterinarians never or rarely contacted physicians.

  • For all the talk about one medicine, this shows how far we have to go.

We need to do a better job of actually practicing one medicine. Veterinarians and MDs need to communicate. Both groups need to realize that they play a role in zoonotic disease prevention, and that the other group has an important role as well. Zoonotic diseases is a niche field in human and veterinary medicine but that doesn't mean they should be ignored. While serious zoonotic diseases are uncommon, they occur, and the failure to actually practice one medicine means that some people are at higher risk than they should be, and infections that occur may not always be identified and managed optimally.

Image credit: UI News Bureau (click for source)

And so it continues...Diamond Pet Food Recall

The title from Food Safety News' latest report says it all: "After eight expansions, how big is the Diamond Pet Foods Recall?" It's disturbing that we can't answer that question, considering the contamination stretches back to 2011 and now it's apparent that there are problems with another one of their plants.

Accordingly to Food Safety News, the FDA has indicated Salmonella contamination has been found in Diamond's Meta, Missouri plant, in addition to the South Carolina plant that's been at the heart of the recall. However, the Missouri Salmonella contamination is from Salmonella Liverpool, a different strain from the South Carolina plant where Salmonella Infantis has been involved. So, there's no evidence that the two recalls are linked, although you have to wonder whether deficiencies that were found by the FDA at the South Carolina plant might also be present at other plants, thus creating an increased risk of Salmonella contamination.

Anecdotal information about sick animals and people associated with this recall abounds, in stark contrast to information from Diamond Pet Foods. It would be nice to have some clear communication from the company about this outbreak, and some information about what they are doing to control it and prevent it from happening again. The continued expansion of the recall and contamination is concerning, and in the absence of clear communication from the company it's hard to have confidence in the safety of any more of their products.

Diamond Pet Food outbreak continues. Diamond Pet Food Communications..not so much.

The large recall and salmonellosis outbreak associated with a variety of foods produced by Diamond Pet Foods continues to expand, in terms of species involved, the number of cases, the number of recalled products and geographic scope. The only thing that's not expanding in information from the company.

Reports (of varying strength) of Salmonella cases in dogs have been cropping up, but it's not just a US problem or a problem only involving people and dogs anymore. Two cats from a Montreal animal shelter have apparently died. At least two people in Canada have also been infected, one each from Quebec and Nova Scotia.

As with many outbreaks, the depth of information is variable when it comes to potential cases and it's hard to say if everything that's reported in the press is real. Just because an animal has been eating recalled food and gets sick, that doesn't mean that the food caused the disease. Testing is required to make the diagnosis of salmonellosis and confirm the involvement of the outbreak strain. However, enough reports are coming in to be fairly convincing that this is a very large, wide reaching outbreak involving people, dogs and cats, and multiple countries.

Communication is critical when managing an outbreak. It can let companies show they are doing everything that's necessary (and more), demonstrate their commitment to correcting the problem, show how they are helping people with affected animals, and provide confidence that once the problem was identified, it was (or will be) rectified and the product can be considered safe. Some companies shine during outbreaks. Some don't.

Here, communications don't seem to be ideal.

  • Another product was added to the recall list, without too much publicity.
  • We know recalled food is in the US, Canada and Puerto Rico (with sick people and animals in at least Canada and the US), but has contaminated food gone any further? Importantly, has information about the potential risk gone anywhere the food might have gone, since the FDA's mandate ends at the US border. eFoodAlert reports some concerning information in that regard. The Taste of the Wild website lists over 50 countries where the food is available and a correspondent for the site apparently bought a recalled product in Ireland. What is actually being done to correct problems that lead to the outbreak is also unclear.
  • I also haven't seen any press releases from the company addressing the numerous FDA violations that were identified in the outbreak investigation.

Outbreaks happen. Sometimes they're not preventable. Sometimes mistakes happen. That's an unfortunate aspect of life. However, how a company deals with those issues, both in terms of correcting the problem and restoring consumer confidence, is critical, and seems to be lacking here.

A good adage when it comes to outbreak communications is "never announce a problem without announcing a solution." That doesn't mean hide outbreak information (something that is done too often). Rather, it means don't just say that you have a problem. Be clear about your problem and at the same time be clear about what you are doing to fix it. Hopefully, Diamond Pet Foods has an aggressive ongoing response to correct these problems, and that's what consumers need to know about. In the absence of any clear information, we're left wondering whether they are doing anything at all.

Bartonella testing in cats: Marketing or science?

People might assume that diagnostic tests are created when researchers identify a condition that needs a new or better test, then develop the test and prove that it works (and helps with patient). However, sometimes it's more a matter of a new test looking for a market rather than a disease looking for a test. Sometimes, it's a matter of an old test trying to maintain a market in the face of new information or better testing. Whatever the situation, the bottom line is that not all available diagnostic tests are useful in all situations.

Bartonella testing is a good example. Bartonella is a strange Genus of bacteria that can cause various diseases in people. Of these diseases, the one most commonly associated with pets is cat scratch disease caused by Bartonella henselaeIt usually causes only mild illness, but serious complications can occur, so it's something to which we need to pay attention.  

National Veterinary Laboratory, a private diagnostic testing company in the US, is currently promoting their Bartonella test, an old test that only indicates previous exposure to the bacterium, as a way to keep yourself and your family safe. In their promotional materials, they state "We recommend that all healthy pet cats, especially those obtained as strays, from shelters or animal rescue organizations, and those that have had flea infestations, be tested for Bartonella infection."

It's not surprising that they recommend testing, since they make money off the testing. But what does the evidence say, and what do experts recommend?

They certainly don't say the same thing as the diagnostic lab. In fact, Guidelines for the prevention and treatment of opportunistic infections among HIV-exposed and HIV-infected children: recommendations from CDC, the National Institutes of Health, the HIV Medicine Association of the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the American Academy of Pediatrics states:

"No evidence indicates any benefit from routine culturing or serologic testing of cats for Bartonella infection or from antibiotic treatment of healthy, serologically positive cats."

So, if an independent group of experts doesn't think that testing of cats owned by this high risk population is necessary, why would we test every cat?

Why not test all cats? For me, it comes down to what the results tell me, and what I'd do with them. For this type of testing:

  • A positive result means the cat has been exposed to Bartonella at some point, and may or may not be shedding the bacterium. There are no guidelines that recommend treating healthy cats, so I'd focus on flea control along with bite and scratch avoidance.
  • A negative result means that the cat has probably not been exposed to Bartonella, but the test isn't 100% sensitive. It also only tells me the status of the cat up to the point that the test was performed, not it's future status. So, the cat could theoretically pick up Bartonella at any point. As a result, I'd 'd focus on flea control along with bite and scratch avoidance.

Why do a test if the end result is going to be the same either way?

Bartonella henselae (along with some other Bartonella species) is an important zoonotic pathogen which warrants our attention.  However, what we need is greater awareness amongst physicians of Bartonella, better cat bite and scratch avoidance and better flea control practices for pets, not unnecessary testing of healthy cats.

Good diagnostic testing is critical for people and pets that might have disease from Bartonella, but not for healthy individuals.

Flesh eating disease from a cat bite

An Albany, Georgia woman is fortunately recovering from necrotizing fasciitis (flesh eating disease) that developed after a cat bite. The cat presumably wasn't the source of the bacterium that caused the disease, but it was the source of the wound that let the bacterium (usually Group A Streptococcus sp) get into her body in the first place, and from there the infection spread rapidly.

In this case, the woman was bitten on the hand by her cat. There's no mention of what she did after the bite, but often people don't take adequate precautions after cat bites because they can appear minor. While the trauma can be minor, cat bites are notorious for causing infections because they can drive bacteria deep into tissues, making it easy for infections to develop.

Four days after the cat bite, the woman's hand "blew up" and she was rushed into surgery. It's an emergency situation because death rates can be high, and those people lucky enough to survive can still have serious complications sometimes requiring measures as drastic as limb amputation, and the extensive tissue damage can lead to chronic problems for the rest of their lives.

People shouldn't worry about getting flesh eating disease from their cat (in part because people don't actually get this kind of infection from cats, it's just that bites can predisposed them to this (and other) kind of infection). However, people should be aware of potential issues associated with bites (from cats in particular, but also from any kind of animal). This case is just one more warning about a range of potential problems that can develop following a cat bite. Any cat bite should be taken seriously and at a minimum promptly and thoroughly cleaned. Bites that occur over the hands, feet, face, joints and similar high risk sites or that occur in people with compromised immune systems should be evaluated by a physician - and sooner rather than later. It's much easier and better to prevent an infection from developing than to try to control an established infection, and while most cat bite infections are mild, serious problems are far from rare.

More information about cat bites can be found on the Worms & Germs Resources - Pets page.

Latest round of rabies news

ProMed's latest accumulation of rabies reports has the typical mix of domestic animal and wildlife rabies cases, and some recurring themes.

Fox / dog / human, North Carolina

In this case, a rabid fox had a "direct encounter" with several people, then it was killed by a dog. Three people have started post-exposure treatment.

  • The article states that the dog was vaccinated against rabies, which is good to hear. However, it goes on to say that exposed pets need to be euthanized or have a 6 month quarantine. In reality, standard guidelines are that unvaccinated pets are treated like this while vaccinated pets undergo a less rigourous 45 day observation at home. Hopefully the discrepancy is simply due to inaccurate reporting and not misinterpretation of guidelines by local officials.

Cat / human, Maryland

A rabid stray cat scratched five people, who have been urged to undergo post-exposure treatment. Officials are calling for anyone who potentially had contact with this cat go to an emergency room.

  • However, odds are if someone goes to an emergency room and says they might have had contact with this cat, they're just going to sit around until someone tells them they don't know what needs to be done, or to go home and deal with someone else. Rabies exposure is a medical urgency, not an emergency. People should take a little extra time to work with their physician and/or public health rather than go to the emergency room.
  • People who may have had contact with the cat need a proper assessment to determine if they were potentially exposed to rabies, since just being around the cat or having casual contact is not a risk. Scratches are a bit controversial since they are low risk for rabies transmission (unless the scratches become contaminated with saliva from the animal), and there are conflicting guidelines regarding what to do for a person who is scratched.
  • This is also a good reminder to stay away from stray cats.

Fox / human, Pennsylvania

In this report, authorities are trying to find a person that cradled an injured fox in a blanket. The fox was subsequently identified as rabid and they need to determine whether the person was potentially exposed to the virus.

  • Again, another reminder to stay away from wildlife, and if there is contact with wildlife, make sure rabies exposure is considered.

Bat / human, Indiana

A student was bitten by a rabid bat while he slept in an Indiana University dorm room. He woke up after being bitten (good thing, since he probably wouldn't have noticed otherwise due to the often tiny marks left by a bat bite).  He is now receiving post-exposure treatment.

Rabies isn't going away, at least any time soon. People need to be aware of the risks in rabies-endemic areas, take care around wildlife and vaccinate their pets.

Photo credit: Rob Lee (click for source)

Flea collar withdrawal in France

A group of flea (or flea and tick) collars have been removed from the market in France following a risk assessment. The review looked at these widely available, over-the-counter products that contain a variety of different chemicals. The determination was that the risks posed by contact with the collars (particularly to children) were unacceptable compared to the benefits.

As with most risk assessments, cost-benefit is the key. With flea collars, you have something containing a chemical that's easily (and commonly) touched by people, and you also have the potential that young children could put them in their mouths. That's the "cost" aspect. The beneficial side is two-pronged. One consideration is the importance of flea and tick control to human and/or animal health. That's certainly significant, since fleas and ticks can be associated with various problems, including infectious diseases and flea allergies. However, the other consideration is whether there are safer and/or more effective alternatives. The answer to that is yes - there are now much better approaches for flea and tick control than flea collars in terms of effectiveness and safety. The disadvantage is that these alternatives are somewhat more expensive and not available over the counter, but the cost and logistics are far from cumbersome.

So, the withdrawal of the flea collars from the market in France is a very reasonable move, and one that needs to be accompanied by information to pet owners that emphasizes that:

  • yes, flea and tick control are still important.
  • there are much more effective options that are safer for the pet and the family.
  • people should work with their veterinarian to determine the approach that best fits their pet(s) and family.

Canine parvovirus in cats

An interesting and frankly somewhat scary report in an upcoming issue of Veterinary Microbiology (Clegg et al 2012) provides further information suggesting that cats might be a source of canine parvovirus infection. This potentially fatal infection, which typically affects young unvaccinated (or inadequately vaccinated) puppies, is a major problem, and outbreaks occur (not uncommonly)  in some high-risk populations like shelters.

In the 1970s, a new form of canine parvovirus, CPV-2, emerged and rapidly spread worldwide. That predates my veterinary career but I've heard stories of clinics where you couldn't turn a corner without stepping on a dog that was hospitalized for treatment of parvo, since it was a new disease and vaccines were not yet available. CPV-2 was shown to be able to grow in cat cells in the lab, but not in live cats, so it was generally assumed that dogs had CPV and cats had their own closely related virus, feline panleukopenia virus (FPLV). However, new variants of CPV-2 have emerged over time, and these seem to have a greater ability to infect cat cells in the lab, and disease caused by these strains has been reported in cats both experimentally and in limited real-world situations. However, it was still considered an uncommon event and the role of cats in parvovirus infection of dogs was largely thought to be inconsequential.

Or maybe not.

In this new study, researchers collected fecal samples from 50 cats in a cat-only shelter, and 180 samples from 74 cats at a shelter than housed both dogs and cats. Canine parvovirus shedding was identified in 33% of cats from the cat shelter and 34% of samples from the dog/cat shelter. A concern with a study like this is cross-reaction of tests for CPV and FPLV, but they went a few steps further to confirm that the virus was indeed CPV, not its feline relative.  They also showed they could grow the CPV from fecal samples in cells in the lab, which means they were detecting live virus in the animals, not just dead viral bits working their way through the cats' intestinal tracts.

The results are interesting and concerning, since they showed that a pretty large percentage of cats in some situations could be shedding live CPV, making them a potential source of infection for dogs (and possibly other cats).

What makes this even more concerning is the duration of shedding that they identified when they collected samples from the dog/cat shelter over time: cats shed the virus for up to 6 weeks, despite appearing healthy.

This raises concerns about the potential role of cats in the spread of CPV. Cats and dogs don't tend to mix much in parks or outside, but CPV is a very tough virus that can survive for a long period of time in the environment.  It's certainly plausible that cats could be depositing CPV-laden feces in the outdoor environment, and since the virus can survive the outdoor exposure and some dogs are notorious poop-eaters, it's a route of transmission that can't be dismissed. Cross-contamination within shelters is also a concern.

The true role of cats in canine parvovirus infection isn't known and it's probably quite limited compared to dog-to-dog spread. However, this study shows that we at least need to be thinking about it and considering cats when dealing with parvovirus problems in shelters and households.

Some things to think about:

  • Young puppies should be kept away from cats, especially strays and cats from shelters, until they are properly vaccinated.
  • Parvo is one more reason to have good physical and procedural separation between cats and dogs in shelters.
  • If a parvo outbreak in underway in a facility, prevention of potential cross-contamination from cats is required.
  • If a cat has been in contact with a dog with parvo, it should probably be considered potentially infectious and kept away from susceptible dogs for at least a few weeks.
  • Canine parvovirus vaccination is highly effective in dogs. If a dog is properly vaccinated, the risk from cats (or other dogs for that matter) is minimal.

Toxoplasma risk factors for cats

There's been a lot of publicity (aka hype bordering on paranoia, including a recent article in the Toronto Star) about the cat-associated parasite Toxoplasma gondii lately. Cats are the definitive host of this parasite and it can cause serious disease in certain people: in pregnant women who have not been previously exposed to the parasite it can infect the unborn fetus, and it can cause severe illness (including neurological disease) in people with severely compromised immune systems. It's also been very loosely implicated in various other conditions, but much of the information gets overblown, as there is lack of solid evidence of a role of Toxoplasma in most of these cases.  Unfortunately, cats end up getting a bum rap in the process, even though most Toxoplasma infections don't come directly from cats.

Nonetheless, toxoplasmosis is a potentially devastating disease in some circumstances. and taking measures to reduce exposure to the parasite makes sense. To do this you need to know what makes cats more likely to be infected, so that these factors can be modified. A recent paper in Preventive Veterinary Medicine (Opsteegh et al. 2012) investigated risk factors for cats having antibodies against Toxoplasma. It's important to note that the presence of antibodies means the cat was exposed at some point and mounted an immune response, not that it's currently shedding the parasite in its feces. Most cats only shed Toxoplasma in their feces for a very short window of time (a week or two) after initial exposure, and that usually occurs early in life. Therefore, it's rare for older cats in households to be shedding the parasite.

The research group found 18% of cats they tested had antibodies against Toxoplasma, and they identified a few factors associated with previous Toxoplasma infection:

  • Age: Younger cats were less likely to have antibodies. The likelihood of having Toxoplasma antibodies increased steadily from 1-4 years of age.
  • Hunting
  • Presence of a dog in the house
  • Being a former stray
  • Feeding raw meat

Most of these make perfect sense and are consistent with other studies. Cats typically get infected by ingesting Toxoplasma cysts found in the muscle of other animals. So, cats that are outside (indoor/outdoor cats, former strays) and hunt, or cats that are fed raw meat are more likely to be exposed. Analysis of the data indicated that hunting contributed the most.

So, while the risk of Toxoplasma infection for the average person is pretty low, some basic management practices can further reduce any risk:

  • Keep cats indoors: This greatly reduces the chance they will be exposed to the parasite. It is also good idea for several other reasons.
  • Don't feed cats raw meat: Cooking meat to the recommended temperature and time will kill any encysted parasites - this also helps prevent exposure of people eating the meat (to Toxoplasma and lots of other bacteria).
  • Control rodents in the house (not by getting a cat!): Indoor cats can still be exposed to various infectious agents through catching mice. I know it's not always easy or even possible (my cat still catches the odd indoor critter) but taking measures to reduce the likelihood of this is wise.

Other important preventive measures include:

  • Changing the litterbox regularly, especially if a high-risk person has to do it. Toxoplasma oocysts need at least 24-48h in the environment to become infective. If feces are removed daily, they don't get that chance.
  • Clean up any fecal accidents and remove any fecal staining of the haircoat (e.g. poop stuck around the rear end of long-haired cats) promptly, before that 24-48h window expires.
  • Wash you hands regularly, especially after contact with the litterbox or any potentially contaminated areas.
  • Wash vegetables and cook meat properly. You're more likely to get Toxoplasma from food than from your cat.

More information about Toxoplasma can be found on the Worms & Germs Resources page.

Methicillin-resistant staph...What's in a name?

I've written about this topic before, but it's an important (and increasingly common) issue to understand, so bear with me while I address the subject again.

I typically get multiple case consults in person, by phone or by email about methicillin-resistant (MR) staphylococci every day. A lot of these start with "I have a case with an MRSA infection..." While trying not to be rude, I tend to interrupt the conversation at that point with "Is this actually Staph aureus or another staph?"

I do this for a few reasons:

  • A few years ago, the vast majority of "MRSA" infections in dogs, cats, horses and other companion animals were actually MRSA - that is methicillin-resistant Staphylococcus aureus. However, in the past few years, there's been a tremendous upsurge in other MR-staph, particularly booming numbers of MR-Staphylococcus pseudintermedius (MRSP) infections in dogs. These days, if it's a dog or cat, when I ask the "What staph is it?" question it's usually not actually MRSA. We're  starting to see more MRSP in horses too, complicating things in that species as well.
  • Staph are divided into two groups, coagulase positive species (which include S. aureus and S. pseudintermedius) and coagulase negative species. The coagulase negative species are commonly found in or on healthy animals and are often methicillin-resistant, but they are not very virulent and don't usually cause disease outside of very high risk populations (e.g. very sick animals in a veterinary hospital). If a MR coag-negative staph is isolated, I am far from convinced it's the culprit, and typically the real cause of the problem still needs to be found.
  • MRSA is much more of a concern from a public health standpoint, as it can move between animals and people. While MRSP can cause human infections, these are extremely rare.
  • MRSA is not really adapted to live in dogs, cats, horses and many other animals. It can, for a while, but doesn't do so longterm, and the vast majority of MRSA carriers will get rid of it on their own. In contrast, it appears that MRSP (at least in dogs) can stay with the animal for a very long period of time. Therefore, an animal that has had an MRSP infection has a reasonable chance of shedding the bacterium for a long period of time, which might be of relevance for its health in the future.
  • The two main MR-staph of concern in companion animals are MRSA and MRSP. Some diagnostic labs still don't try to differentiate the two, despite the fact that there are different guidelines for determining whether they are methicillin-resistant. If someone has a result that doesn't differentiate MRSA from other staph, I tell them their lab isn't doing things right and they need to talk to them so they can have confidence in the results.

More information about MRSA and MRSP can be found on the Worms & Germs Resources page.

Severe Pasteurella infections from palliative pet care

Pasteurella multocida is a bacterium that's commonly found in the mouths of dogs and cats. It's a common cause of cat and dog bite infections in people, but can also be spread through close contact with pets (without bites). It's logical to assume that the closer the contact, the greater the risk of transmission. A recent report in Clinical Infectious Diseases (Myers et al 2012) describes three people with life-threatening Pasteurella infections. A unique aspect was all three people got sick from nursing dying pets.

Case 1

  • A 55-year-old woman with sore throat, fever and difficulty swallowing was diagnosed with epiglottitis (inflammation of the epiglottis, a part of the throat region) and hospitalized. Pasteurella multocida was identified on a blood culture.  It was subsequently revealed that she had provided palliative care to her dying dog. As part of this, she was dropper-feeding the dog honey, and also eating honey with the dog from the same dropper.

Case 2

  • A 63-year-old woman with sore throat, difficulty swallowing and hoarseness was diagnosed with uvulitis (inflammation of a different part of the throat region) and narrowing of her airway. As with Case 1, P. multocida was isolated from her blood. Her cat had died six weeks earlier and she had "continuously held, caressed, hugged and kissed her cat during its last 7 days of life."

Case 3

  • A 66-year-old woman was hospitalized with fever, chills, cough and difficulty breathing. She had severe pneumonia and P. multocida was grown from a sample of respiratory secretions. Two weeks before she got sick, she had provided palliative care for her dying cat, by "holding, hugging, and kissing the head of the cat and allowing the cat to lick her hands and arms."

Fortunately all three women recovered from their infections, but the severity of disease is certainly a concern. As is common, there was no attempt to see whether the implicated pets actually carried the same Pasteurella multocida strain as the owners, but here the authors at least had a good excuse, since all of the pets had died before the owners got sick.

There are some interesting points in the Discussion section of the paper.

"Our 3 patients’ histories of having recently provided palliative pet care to their dying animals were obtained only after P. multocida was identified in cultures and only after subsequent detail-oriented, animal contact histories were obtained."

  • Pet contact (or animal contact in general) is still not asked enough by physicians investigating unknown illnesses. It's unclear whether it would have made a difference in these cases, but knowing more and knowing it earlier can help speed the path to the right diagnosis. Here, pet contact was only considered after a pet-associated bacterium was identified.

"Simply asking whether or not the patient had a pet would not have uncovered the defined association of these respiratory illnesses with palliative pet care. The patient with P. multocida uvulitis even denied having a pet (it had died 6 weeks previously) and only admitted to having provided palliative pet care when asked specifically if she had any animal contacts in the past 3 months."

  • This shows some of the challenges and how care must be taken when asking about pet contact. Simply asking "Do you have a pet?" doesn't cover it.

"Only diligence and very detail-oriented, pet-related histories will likely uncover further patients with invasive P. multocida infection related to the pet owner’s provision of palliative pet care to dying animals."

  • This shouldn't be focused on palliative pet care, since that's a minor component of pet contact. Many other people have close contact with their pets, even when the pets are healthy. It's something that should be considered at all times.

Bordetella infection from cat to child

Case reports of infections acquired from pets are sporadically found in the human medical literature. A common problem with these reports is the failure to look for true evidence of zoonotic transmission. The typical thought process is "We found this bug in a person, it's most often found in animals, so this person must have gotten it from their pet." Often, this likely is actually the case (although some evidence would be nice). In other instances, like the Pasteurella bone infection described in the Orthopedics paper I wrote about recently, this assumption is probably completely off-base.

Something that is usually missing from these reports is any investigation of the suspected pet. Finding the bacterium in question in/on the pet, and showing that it's the same strain as was found in the person goes a long way to supporting the conclusion that the pet was the source. It's not a 100% guarantee, since you can't say whether it went from pet-to-person or person-to-pet, but with a typically pet-associated bacterium its much more likely to have come from the pet, so finding the same strain in both pet and person is pretty solid evidence. Most case reports don't bother even trying to get this much information (but they still get published...).

A case report in an upcoming edition of Zoonoses and Public Health (Register et al 2012) is another example of a study that provides some information about a potential pet-associated infection, but stops short of the type of proof that is needed. To their credit, the pet wasn't available for testing and they are clear that it's a "possible" case of zoonotic transmission, which puts them a step up on other studies, but it's still too bad the additional information couldn't be reported.

The case report describes an 11-year-old girl with cystic fibrosis (CF). People with CF are at greatly increased risk of respiratory infections, including infections caused by microorganisms that typically don't cause disease in other people. This child had a sputum sample collected during a routine doctor's visit, when she didn't have any signs of respiratory infection. Bordetella bronchiseptica, a bacterium most often found in dogs and cats (and one of the causes of kennel cough (aka canine infectious respiratory disease syndrome) in dogs), was isolated from the sample. When this was explored further, it was revealed that child's family had obtained a new kitten three weeks earlier, and the kitten had signs of respiratory disease.

Unfortunately, the kitten had been removed from the household by the time B. bronchiseptica was diagnosed in the girl, so it couldn't be tested. (They don't say why the family got rid of the cat.) However, the authors at least took it a step further and did some detailed molecular characterization of the bacterial strain they recovered from the sputum sample. Different genetic traits suggested that the strain was feline in origin, and, combined with the fact that the child had contact with the kitten, this provided a little more support to the hypothesis that the cat was the source. It's not proof, but still interesting. They also determined that the B. bronchiseptica strain was missing a gene that's associated with helping cause disease, suggesting it's not as able to make people sick. That might explain why the child was carrying the strain in the absence of disease, although people can carry lots of different bacteria that can potentially cause disease without being clinically ill.

In the end, it was an interesting little report and the authors conclude with a couple of good statements:

"Acquisition of detailed clinical and epidemiological data paired with discriminatory genetic comparison of case isolates and contact isolates is needed to more firmly establish transmission patterns and identify likely contact risks." (A fancier way to say what I said above.)

" seems advisable to counsel CF patients regarding adherence to practices that minimize opportunities for zoonotic transmission of B. bronchiseptica from family pets or other potentially infected animals."

Niagara (NY) SPCA under scrutiny

The executive director of the SPCA of Niagara is under pressure from charges that he's "presided over the killing of hundreds of animals." As is common with shelter controversies, sorting through the emotion and rhetoric is difficult. At best, running a shelter can be a thankless task, due to the overwhelming number of animals, emotion, lack of understanding by the public (and often personnel) of the relevant issues, financial challenges and often poorly designed facilities. At the same time, bad things do happen in shelters, and it's critical to put in the time and effort to determine whether things are being done poorly and what needs to be fixed. Here are some of the issues from the Niagara situation.

"From Oct. 1 to Dec. 15, the local SPCA euthanized 473 cats and 100 dogs, a staggering total of killings, according to sources familiar with the situation at the Lockport Road shelter."

  • Apart from the problem of relying on information from anonymous sources, it's hard to put this number into context. You need to know the overall number of animals that come in and the shelter's capacity. It's a sad fact that about 50% of cats are euthanized at most shelters internationally because of massive overload. Shelters shouldn't be cat warehouses. It does no one (including the cats) any good to stockpile huge numbers of cats that never have a chance of adoption, and it creates a perfect environment for disease outbreaks. So, while that number of animals seems high at first glance, it may just reflect the reality of supply and demand, shelter capacity and the health/adoptability status of the animals.

"When he was hired, Faso admitted, “My animal care experience is very minimal.”"

  • A shelter director doesn't need to be an expert in shelters and animal health. In fact, some excellent shelter directors have come into the job with no experience whatsoever. Their job shouldn't be running animal care. They should be running the shelter, managing personnel, raising funds, liaising with the community and doing a host of other activities. The key is having good veterinary and animal care support, and a willingness to listen to those people. It would be great if every shelter manager was a veterinarian with a shelter medicine residency under his/her belt, along with an MBA and training in communications, but that's not going to happen. Someone with little animal knowledge but the ability to listen and take advice can be an excellent shelter director.

"McAlee and others tell horror stories of animals brought to the shelter for surrender or picked up on the streets and in need of medical care, who are then left to suffer in their cages. In one case, a cat that appeared to be suffering from a broken jaw was brought in and allowed to stay for a week in a cage without treatment. Finally, a concerned staffer took the cat to an emergency veterinary clinic where it was treated and then returned to the shelter."

  • That's a big problem. If true, and if this was done because of pressure from the director overriding advice from medical staff, then that's completely inappropriate. Interference with medical decisions and medical care does occur in some shelters and is a major problem.

"When the cat then developed a common respiratory infection, rather than provide further medication for the animal, Faso directed that it be euthanized."

  • This is a tougher issue. I hate to see potentially treatable animals euthanized, but euthanasia is an appropriate response in some situations. If they are unable to properly manage an infectious case or are overwhelmed with healthy cats, keeping an infectious cat may pose a huge risk to all of the other cats in the facility. It's impossible to say much here without more details.

"Other sources tell the Gazette that cats at the shelter have been injuring themselves in out-dated display cases and that a donor offered to fund the replacement of those cages. Faso, reportedly, refused to accept the donation."

  • Poor housing is a common problem in shelters. Good cages are expensive. It would be bizarre for a shelter manager to turn down money (that came with no strings attached) and if that was done, it would be another sign that Mr. Faso's not right for the job.

"..he has reportedly told board members and others that the local SPCA will “never be a no-kill shelter because it’s too expensive."

  • That's an unfortunate fact. No kill shelters just aren't viable in the grand scheme of things. Individual shelters can be no kill, but that's often done by cherry picking the adoptable animals.

It comes down to math. If 50% of cats coming into shelters are euthanized every year because of lack of space, to convert to a no-kill approach we'd need to massively increase shelter capacity every year to accommodate the increasing population. Millions of dollars would be required to create cat warehouses where millions of unadoptable cats lived marginal lives in facility confinement until dying of natural causes or from the massive disease outbreaks that would be certain to happen. I know I'll get reams of emails complaining about this paragraph, but to me it's a simple fact. If you increase supply by 100% per year by not euthanizing any animals, and demand doesn't increase, the math quickly shows you the size of the problem that would be created.

The only way to get to the point where no-kill is a viable approach is to have more responsible pet owners and better animal population control. Euthanasia rates are much, much lower in dogs, in part because of much better population control and also because people tend to try harder to recover lost dogs compared to lost cats. Recovery rates of lost dogs that make it to shelters are very high. Cats... not so much.

So, if you want to help out shelters and the animals in them:

  • Spay and neuter your pets.
  • Donate to good quality shelters to help them provide optimal care.
  • Volunteer, if you have the time and interest.
  • Hold shelters to a high standard, but make sure it's a realistic standard.
  • Encourage municipalities to properly fund animal shelters and enforcement.
  • Consider adopting from a shelter if you are getting a new pet.
  • Take the time to learn about the issues, and make assessments based on fact, not just emotion.

Variable pet bite advice

It seems like pet bite articles come in waves, with a recent cluster showing the variable quality in advice that's available.

Often, they are holiday "filler" articles that provide some basic useful information but overall are of limited use or even harmful based on their very superficial approach. They often mention rabies, get a quick quote from a veterinarian or someone in public health, but don't emphasize the potential problems that can occur with even apparently minor bites. The thing that often raises my ire is the common statement about watching the bite and going to a doctor if your limb swells up or has pus oozing out, without talking about the need for proper post-bite care to actually prevent that from happening.

Anyway, I came across a couple of better articles recently, that get some good information across in a nice, readable manner. One, an article in "The Herald News" entitled "Cat bites always require check by doctor", gets a very important point across quickly.

The news story details the saga of the PJ, a 13-year-old cat, and his owner. PJ bit the woman on the arm causing a seemingly minor wound, but by the next day, her arm was red and swollen, necessitating a round of intravenous antibiotics and four days in hospital. In the article, Gail Steele, an infection prevention nurse, states "Cat bites.. must always be considered medical emergencies. This is especially true when they occur in the hand because that area has a richer blood supply...Their sharp little teeth are like little needles, and they inject bacteria right into soft tissue..."

This is a pretty extreme example of what can happen after a cat bite, but it's far from rare. It's not really clear whether this person's infection would have been prevented with normal practices. Bites over certain sites, like the hand, foot, joints, tendon sheaths and prosthetic devices, and bites to young kids, elderly individuals and people with compromised immune systems typically require prophylactic antibiotics.

If this was actually a bite over the arm, as reported, antibiotics might not have been given, even though cat bites are much higher risk for infection than dog bites. However, the key is that bites should be assessed so proper determination can be made about the need for antibiotics. All infections won't be prevented but appropriate medical care should reduce the risk and also allow for adequate consideration of whether rabies exposure might be a concern.

There's a sad end to this article, as PJ bit his owner again a few months later. The bite was over the shin and, given her previous problems, antibiotics were provided. However, the owner still ended up with an abscess that required surgical intervention and took months to heal. (Whether this person has really bad luck, whether PJ has a particularly bad mix of bugs in his mouth or whether the owner has an unidentified problem with her immune system is unclear, but back-to-back severe infections is a major issue, especially with a cat that is prone to biting.) The woman's daughter ended up taking PJ home with her, but after another unprovoked bite, he was euthanized.

Cat bites aren't always this bad, and in fact, most don't result in complications. However, that's not to downplay the potential problems. When you consider how often cats bite, how often cat bites are not properly cared for because they appear to be minor, and the ability of a cat bite to inoculate bacteria deep into the tissues, it's easy to see how bad things can happen. Reducing the risk of cat bite infections involves a few basic steps:

  • Reducing bites. Good handling and training (of both cats and people) can reduce the likelihood of bites. This is particularly important with kids, who may be bitten through rough or excessive handling of a cat.
  • Bite first aid. Prompt cleaning of the wound can reduce bacterial contamination. Thorough cleaning with soap and water can have a big impact on the likelihood of infection.
  • Medical care. Bites over certain sites or to certain individuals (see above) almost always require antibiotics. There's less consensus over other types of bites, but getting medical care is a good idea in any case to determine if there are any factors that indicate a need for antibiotics.
  • Rabies avoidance. Every bite should be reported to public health so the rabies aspect can be covered. The biting animal needs to be identified and observed for 10 days. If it's healthy after 10 days, it couldn't have been shedding rabies virus. If the biting animal cannot be identified, it's likely that post-exposure treatment for rabies will be required.
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Cats as dinner guests

To each his own, I guess. Today's Toronto Star has an article on the front page of the Life section about the Shine family and their rather close dining relationship with their four cats.

Among some of the highlights:

One of the front page pictures shows one of the cats standing on the counter while food is being prepared.

  • Would you want your cat to sit on your food before you ate it? Probably not. Would you lick the cat's feet after it got out of the litter box? Doubt it. By letting the cat sit on the food preparation area, aren't they essentially doing the same thing?

The cats' food and water bowls are on the kitchen counter.

  • Feeding pets in the kitchen was a risk factor in a Salmonella outbreak linked to contaminated pet food (Behravesh et al. 2010). That's just feeding them in the kitchen, let alone on the counters.

The other front page picture shows a different cat licking dinner rolls before they are being served. "I'll eat that one" declares the husband, an anesthesiologist (to check out the photo gallery, click here)

  • This maybe has a greater "ick factor" for most people, but in reality is probably much lower risk than the first two issues.

Yet another picture (slow news day?) shows a cat stretched out on the dining room table while the rest of the family eats.

As I said above, to each their own. People can make their own decisions about how to interact with animals. It doesn't seem like there are any young children (who are subjected to their parents decisions) to worry about in the household. However, it's unclear whether there might be any other high risk persons in the household to be worried about. Mrs. Shine has diabetes, and that can be associated with effects on the immune system. Further, what about other people that visit the house (or come over for dinner)? Are any of them high-risk individuals, and do they know about the potential risks? Who knows? (The Shine's say they don't have people over for dinner often.)

What's the real risk? It's hard to say. It's probably low but we know:

  • people can get infections from cats
  • many of the infections that people get from cats are acquired by ingesting microorganisms from these animals
  • certain types of pet management (e.g. feeding them in the kitchen) have been associated with higher risk of infection

I'm all for close contact with pets and making them part of the family. If my cat jumps up on the dining room table during the day, I don't panic and try to sterilize it (the table, that is). However, I try to maintain a balance between having my pets as part of the family and not having their microorganisms as part of my family.

There are much worse things that you can do with your pets than are demonstrated here, but I can't believe that it doesn't increase the risk of disease. Maybe for this family, they are willing to accept an increased degree of risk for the benefits they perceive. Unfortunately, I doubt they have really thought about the potential infectious diseases issues or talked to someone about them, to let them make a truly informed decision. (Perhaps (hopefully) their other daughter, who is currently attending vet school overseas, will be able to provide them with some more information on this topic when she gets home!)

New York hotel-cat restrictions

New York City's Algonquin Hotel has a feline tradition of sorts - namely having a resident cat to greet people in the lobby. Matlida III is the tenth in a line of hotel cats that dates back to 1932.  She has her own page on the hotel's website, and her own email address. Yet the City's Department of Public Health has issues with the hotel having both Matilda and another tradition - food in the lobby - co-existing.

According to the hotel website, the cat normally has the run of the building except for the dinning room and kitchens.  However, since the hotel also serves food in its lobby, it's running afoul of the health code, which prohibits pets in any area where food is served. (Interestingly, the news article says there's an exception for restaurants that serve seafood. I'm not sure why, but I guess we all know cat's would never go for seafood...). Therefore, Matilda is now being kept on a leash and restricted to the reception desk, main entrance and coat room. 

So, does any of this make sense? There's no clear answer, and like a lot of other infectious disease issues, it comes down to cost/benefit. Every human/animal encounter comes with some risk of infectious disease transmission, as does every human/human encounter. Some things increase the risk, while others can decrease the risk.

Having food served around animals increases the risk of disease transmission, because many of the infections we're concerned about are transmitted by ingestion of bacteria and parasites from animals. Based on that, it seems like a reasonable rule, even though it's probably much more likely that someone would contract an infectious disease from a person in the lobby than from the cat. Ideally, they'd figure out a way to have the food in another area so the cat could still roam the lobby without having access to the food serving area itself, but that may not be an option for the hotel.

One thing that often gets overlooked in these discussions is allergies. In reality, allergies are probably the biggest human health issue with a situation like this. Some people are extremely allergic to cats and wouldn't expect to encounter a cat in a place like this. An unexpected cat encounter could cause significant discomfort for some allergic individuals. Letting the cat hang around the coat room raises similar concerns because of the potential for contamination of peoples' coats with fur and dander.

Issues like this tend to generate a polarized response, with some people outraged at the cat's restriction and others outraged at peoples' outrage, reasoning that a hotel lobby is no place for a cat.

Condolences can be sent to Matilda via her personal email address:

Raw diets...again

CTV has a consumer reports segment and a recent topic involved feeding pets "natural" diets (although no one ever defined what that really means). In the report on the CTV Consumer Alert website (it's currently about the third story into the video if you just press play, or you can shortcut to it using the link below the main video window), a 26 year old cat is held up as a poster child for the health benefits of raw food. Making it to 26 is a noteworthy accomplishment for a cat, but it's far from rare, and you can't know whether the cat survived because of its diet or despite its diet. At the end of the clip, they mention he cat has kidney disease, not an uncommon problem in older cats but one that is often blamed by raw proponents on commercial foods. It's also not a condition that I'd want to see someone try to manage with a raw diet.

Anyway, the story has the typical statements (including one from a veterinarian) about how raw and "natural" diets produce a healthier animal, stronger immune system and shinier haircoat, but without citing any proof (because there is none) and with no discussion whatsoever about the potential animal and public health impacts of raw meat feeding.

Good investigations are good. Quick reports put together with little thought or consideration of the issues are just time filler. The host, Pat Foran, said in his conclusion that "natural" pet foods have less filler so there's less to come out the back end of the dog. Well, news reports comprised of filler produce the same kind of by-product.

If you are going to feed raw, at least take the time to research how to do it safely, both for your pet and your household. Raw feeding can be done in a nutritionally sound manner, but it takes time, effort and money. Some people are willing and able to do that, but if you're not, don't feed raw. Raw feeding also carries some risk of gastrointestinal disease like salmonellosis in the animal as well as exposure of people in the household to those same bugs. Certain households, particularly those with high risk individuals (e.g. elderly, infants, pregnant women, immunocompromised persons) should avoid raw feeding or only use products that have been high pressure pasteurized. There are a few commercial raw diets that are treated in this manner and these are preferable as the process should kill most relevant bacteria, reducing or eliminating the infectious disease risks to pets and people.

Like many other things in life, the key is being informed so you understand the risks and benefits, and whether recommendations made by people have any substance behind them. Too often, people make a major change like feeding raw based on a comment on a website or from another dog owner, with no clue about the issues and no effort to figure out how to do it right. That's just asking for problems.

More information about raw diets can be found on the Worms & Germs Resources page.

Raccoon invaders and roundworms

Here’s a recent question I received:

 "My problem is that the raccoon broke a window, came into my house, ate the cat food and then defecated on the kitchen floor. Since they went a day without food, the cats may have eaten the few bits of food that were left behind. How can I tell if they got the roundworm?"

It’s a reasonable question given the concerns about Baylisascaris procyonis, the raccoon roundworm. However, there’s basically no risk. While it is very likely that the raccoons were shedding roundworm eggs in their feces, those eggs are not immediately infective. Ingesting a "fresh" roundworm egg isn't a risk. Eggs have to sit around in the environment for at least 11 days (typically 14-28 days) before they become infective. Therefore, unless the feces are allowed to sit around in the house for a couple of weeks, roundworm infection isn’t a concern in such a case.

Animal shelter outbreaks

Infectious diseases are continuous challenges for animal shelters. Unfortunately, outbreaks are not uncommon. Sometimes they're the result bad luck and the inherent risks involved in bringing together  lots of animals of questionable health status from different sources. However, if you compound these risks with things like inadequate facilities, overcrowding, poor training of personnel, poor adherence to protocols, bad protocols, lack of awareness about infectious diseases and failure to get expert help early in any outbreak, the likelihood of "badness" increases.

A few shelter outbreaks are underway at the moment, and they highlight some of the infectious disease challenges posed by different diseases in animal shelters.

  • The Oakville and Milton Humane Society (in Ontario) is closed because of a ringworm outbreak that's been going on since early September. Ringworm, while of limited health consequences, is an important shelter problem because it's common, highly transmissible, can be hard to control and can infect people. At last report, 22 cats were confirmed or suspected to have ringworm, along with at least four staff members. It's not clear who's coordinating the outbreak response, but hopefully they're getting good advice and they've read the comprehensive report from the Newmarket OSPCA ringworm debacle.
  • 72 kittens were euthanized in the Miami-Dade County Animal Services because of "cat plague," which is a common name for feline panleukopenia. This viral disease is preventable by vaccination, but it's a serious concern in shelters were there are often lots of unvaccinated or inadequately-vaccinated cats and lots of susceptible kittens. In this shelter, all cats with clinical signs consistent with panleukopenia are being euthanized. Euthanasia is always a tough decision, but with a serious disease like this, it's a reasonable response. Outbreaks like this highlight the need for excellent infection control practices to reduce the risk of spread of pathogens like this once they make it into a shelter.
  • Upper respiratory tract infections have resulted in suspension of adoptions at the Bergen County Animal Shelter in New Jersey. News reports are calling it a canine influenza outbreak, and canine flu is definitely on the list of possibilities, but it doesn't sound like it's been confirmed. Respiratory infections are a common cause of problems in animal shelters because some causes (e.g. canine parainfluenza virus, canine influenza virus) are quite transmissible. Canine flu poses extra challenges when it moves into a new area, since few if any dogs have antibodies against the virus and therefore it can spread rapidly. The report also mentions transmission by dogs not showing signs of disease. That's a problem with some infectious agents. For example, with canine flu, dogs tend to be able to shed the virus before they show signs of illness. Therefore, there's a period of a couple of days after infection but before disease where you can have a silent reservoir of infection. That's why quarantine of new admissions is critical, since it gives animals a few days to show signs of diseases they may be brewing at the time of admission. (Unfortunately, it's not easy to find space in which to quarantine an animal in an overcrowded shelter.)

A common denominator in all of these outbreaks is the potential that something could have been done differently to prevent the problem. It's possible (although unlikely) that everything that was done perfectly, however it's a rare outbreak where you can't find multiple areas for improvement. A key aspect of outbreak management is, once the crisis is over, performing an investigation of what really went wrong and why, and taking measures to reduce the chance of it happening again.

Image: Ringworm infection in a cat is not always readily apparent, but in some cases can cause obvious patches of hair loss.

US Rabies update, 2010

The CDC's annual animal rabies surveillance report has been published in a recent edition of the Journal of the American Veterinary Medical Association (Blanton et al 2011). It's the regular synopsis of the state of rabies in domestic animals and wildlife in the country. It contains some interesting information but few surprises. Among the highlights:

  • Rabies was identified in 6154 animals in 48 US states, plus Puerto Rico. The true number of animals that died of rabies in the year would have been much higher, since not all animals (particularly wildlife) that die of rabies get tested.
  • 92% of positive animals were wildlife, including raccoons (37% of cases), skunks (24%), bats (23%) and foxes (7%).
  • Cats were the most commonly affected domestic animal, accounting for 4.9% of cases (303 cats), followed by cattle (1.1%), dogs (1.1%) and horses (0.6%).
  • Different rabies virus variants predominated in different regions. For example, raccoon rabies virus was most common on the east coast. Different skunk rabies variants predominated in the south-central and north-central regions, along with California and Nevada. A couple of pockets of fox rabies were present in the southwest, along with one in Alaska. Mongoose variant was present in Puerto Rico. Bat variants were spread out across the country.
  • Most rabid cats were from states where raccoon rabies is endemic. About 1/3 of infected cats were from Pennsylvania and New York. Texas was the leader in dog rabies, followed by Puerto Rico and Virginia.
  • Two cases of rabies in humans were identified, compared to 4 in 2009. One was a migrant worker infected by a vampire bite while in Mexico. The other was a man from Wisconsin who was infected with a bat rabies strain. Both died.

Canadian and Mexican data are also reported:

  • 123 cases of rabies were identified in Canada, 93% of which were wildlife. 7 (5.7%) were dogs or cats. No rabid raccoons were identified, continuing a trend that has been observed since 2009. Bats and skunks were the wildlife leaders. No people were infected.
  • 357 cases were reported in Mexico. 83% were cattle, 20 were dogs. Four human cases were identified.

While rabies does not exert anywhere near the impact on people in North America compared to many other regions (where tens of thousands of people die from the disease every year), it continues to take its toll on wildlife and, to a lesser degree, domestic animals. It's also a preventable disease that can be controlled with vaccination, and human cases can effectively be eliminate by proper post-exposure treatment. Continued efforts are needed to reduce rabies in wild and domestic animal populations, for both the protection of those populations and protection of the people who may come in contact with them.

(click image for source)

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World Rabies Day

While it's not really an occasion to celebrate, September 28 was World Rabies Day. Rabies has been a problem for millennia, and it's not going away any time soon. This viral disease, which is almost invariably fatal, kills 50 000 - 70 000 people per year. Some countries have astounding rates of rabies cases, such as India where ~20 000 people die of the disease every year. Internationally, most human rabies infections are caused by dogs, but wildlife are the main source in some regions (such as Canada and the US) . Basically all rabies infections are preventable with proper access to good medical care and rabies post-exposure prophylaxis, but sadly the thousands of people who die do not receive treatment.

Is rabies controllable? Yes. With measures to reduce rabies in wild and stray animals, pet vaccination, public education measures, good access to medical care, adequate rabies vaccine supplies and adequately trained healthcare personnel, the incidence of rabies can be dramatically decreased. However, these measures require time, money, effort and political will, and those are limitations in some areas.

Can rabies be eradicated? That's a tough question. Eradicating a disease that can be found in many wild animal species internationally is extremely difficult. It's hard to envision complete eradication of this virus, as was done for smallpox (a human-only disease) and rinderpest (a cattle-only disease). Both those diseases had the advantage of only being found in one species, making control and eradication much more feasible. However, while we might not be able to eradicate rabies, it's certain that tens of thousands of lives could be saved every year with good rabies control programs.

More information about rabies can be found in on the Worms & Germs Resource page.

Corynebacterium ulcerans infection from a cat

The latest edition of Emerging Infectious Diseases (Berger et al 2011) describes a case of Corynebacterium ulcerans infection in a women that was likely acquired from her cat.

Corynebacterium ulcerans is a bacterium that's related to C. diphtheriae, the cause of diphtheria. Some strains of C. ulcerans can produce toxins that cause diphtheria-like disease, and with the success of diphtheria vaccination, C. ulcerans is now the leading cause of diphtheria-like disease in people in some regions. Typically, C. ulcerans infections are associated with ingestion of contaminated milk or dairy products, but reports of infections acquired from dogs and cats appear to be on the rise. As is often the case, whether this is because it's becoming more common or that people are simply looking more is unclear.

In this report, a woman from Germany developed diphtheria-like disease, including a sore throat, ear ache, hoarseness and nasal obstruction. A swab was taken from her nose and throat, and toxigenic C. ulcerans was isolated. She didn't report any livestock contact and had not traveled abroad, so other possible sources of infection were considered, particularly other types of animal contact. She had a cat, so nose and throat swabs were collected from her pet, and the same strain of C. ulcerans was isolated.

With this type of investigation, you can't prove that the cat gave the bug to the owner. Since the cat was healthy and tested after the owner was sick, you can't say for sure whether the cat was the original source or if it was infected by the owner. However, with a bug like C. ulcerans that has been associated with pets before and that can be carried by healthy cats, the conclusion that it came from the cat is reasonable. The cat was treated with antibiotics and C. ulcerans was not detected after treatment.

This is an interesting report.  It's always good to see people thinking about the relationship between human and animal disease, but at the same time, it's important to put this into context. Yes, C. ulcerans is a potential zoonotic concern, but it's rare. Anytime you see a case report involving a single person in the medical literature, you know it's either something new or very rare. In this case, it's the latter, since we know from previous reports that this bug can cause human infection and be transmitted from animals. Rare doesn't mean never, and you can't dismiss it, but C. ulcerans is just one of many bacteria that can be found in cats and transmitted to people. It's part of the inherent risk of infection that comes with cat ownership. This relatively low risk is hopefully outweighed by the benefits of cat ownership, and the cost-benefit can be maximized by basic infection control and hygiene practices. This report also shows how it's important for physicians to query pet ownership when dealing with infectious diseases in their patients, something that still needs lots of improvement.

Bordetella bronchiseptica infection in a cancer patient...kitten suspected as source

A paper in the Journal of Neurooncology (Redelman-Sidi et al, 2011) describes "kitten-transmitted Bordetella bronchiseptica infection" in a cancer patient. The patient in question had a brain tumour that was surgically removed. The 56-year-old man was then started on chemotherapy, which in addition to killing cancer cells can also cause significant impairment of the immune system, which puts chemotherapy patients at high risk for infections of many kinds. This particular patient developed a persistent cough during treatment and was eventually diagnosed with B. bronchiseptica infection. This bacterium is one of the causes of kennel cough in dogs, and can cause respiratory infections in other species, including cats.

The man had acquired a kitten three weeks before he developed the cough. The kitten had (at some undefined time) conjuncitivitis and signs of respiratory disease. Unfortunately, as is too often the case in reports of supposed pet-associated disease in the medical literature, the kitten was not actually tested.  Bordetella bronchiseptica is classically an animal-associated organism, the kitten was newly acquired and it had respiratory disease.  These factors strongly suggests the kitten was the source.  However, without testing of the kitten and investigation of other potential sources of infection, it's hard to be as definitive as the title suggests. The suspicion of the kitten being the origin is reasonable nonetheless.

Some statements from this report are contrary to my typical recommendations for pets and immunocompromised individuals.

Getting a young animal

  • Kittens and puppies are entertaining, but they are also higher-risk animals compared to adult dogs and cats. They are more likely to harbour a variety of infectious agents. They are also more likely to bite or scratch through playful or rambunctious behaviour, and it's harder to properly assess their temperament. If an immunocompromised person wants to get a new pet, getting an mature animal is ideal.

Source of the kitten

  • The paper unfortunately doesn't mention from where the kitten was obtained and whether there was a respiratory disease problem in other animals at the source. Animals in shelters, humane societies and pet stores are more likely to carry various infectious diseases because they are densely populated facilities, often have infection control challenges, house many high-risk animals and are stressful environments. Getting new animals from these places is not ideal for a high-risk person.

Veterinary care

  • The kitten had signs of respiratory disease and was seen be a veterinarian. It doesn't appear that any testing was done and the kitten was just treated with antibiotics. That's pretty common, but in a situation where there is a high-risk person in the house, it's wise to be more aggressive with diagnostic testing to determine whether there may be any concerns for the person.

A pet can be a wonderful thing for a person living cancer, by providing social and emotional support, along with other benefits. Pet ownership always carries some risk of zoonotic infections, and the risk is higher in people with compromised immune systems. Rarely, if ever, is pet ownership inappropriate for a cancer patient, although certain pets and certain situations might be, and high-risk individuals need to think about possible risks and measures to reduce those risks.

People with cancer or other problems affecting their immune system should ensure that their physician knows that they own pets. Veterinarians need to play a role as a member of the overall healthcare team too. Optimizing pet health can help reduce the risk of human infection. Prompt and proper diagnostic testing can identify potential issues. Proper counseling can reduce risky situations from inappropriate pets, inappropriate contacts and other factors that might make exposure to a nasty infection from a pet more likely.

Toxoplasma and brain cancer?

A recent paper about toxoplasmosis in the journal Biology Letters (Thomas et al. 2011) has attracted a lot of attention because it reports a possible link between this cat-associated parasite and brain cancer in people.

Toxoplasma gondii is a protozoal parasite. Cats are the natural host and can (but rarely do) pass the parasite oocysts (eggs) in their feces. People can be infected by ingestion of Toxoplasma oocysts that have been outside of the cat long enough (24 hours or more) to develop into an infectious form. Human Toxoplasma exposure is common, although this is typically not acquired directly from pet cats.  Adult cats rarely shed oocysts, whereas exposure from contaminated soil (e.g. from working in a garden and not washing ones hands afterward) or undercooked meat of various kinds are also important sources in different areas. Almost always, when a person gets infected, disease does not occur. Rather, the immune system contains the parasite, but is unable to kill it completely.  The parasite therefore often enters a dormant state forming small cysts in various body tissues, including in the brain.

Most concern regarding Toxoplasma involves pregnant women who have not been previously exposed to the parasite (and therefore have no antibodies to fight it off quickly). If they become infected during pregnancy, serious infection of the fetus can occur. Another problem in people is Toxoplasma encephalitis, a severe brain condition that occurs most commonly in people with compromised immune systems (e.g. HIV patients), typically from re-activation of dormant Toxoplasma

The recent paper by Thomas et al raises an additional concern: brain cancer. The basic premise of the paper is that some types of persistent infections might be able to induce mutations at the cellular level, resulting in cancer. Since Toxoplasma can cause longterm but dormant infection in the brain, they investigated a possible linkage.

The researchers took international statistics about malignant brain cancer from the International Agency for Research on Cancer database to determine brain cancer rates in different countries. They then compared these to Toxoplasma antibody rate data from 37 countries (from a 2006 paper that collected data from other papers). They found that the prevalence of antibodies against Toxoplasma in a country was related to the prevalence of brain cancer in the country (that's an oversimplification of what they did, since they did various kinds of statistical analyses, but that was their basic conclusion).

Some things to consider, though, before you ask for an MRI because you're a cat owner:

  • This is a pretty superficial study. When I started reading it, I assumed they had done a case-control study, whereby they took a group of people with brain tumours and an equivalent group of people without brain tumours, and compared Toxoplasma antibody rates. That's not what was done. Rather, what they are essentially saying is that the incidence of brain tumours is higher in countries with a higher incidence of Toxoplasma antibodies in people. There are potentially a lot of other factors that might be involved. For example, they also showed that the incidence of brain cancer increased with increased gross domestic product (GDP) of the country, i.e. brain cancer rates are higher in wealthier countries. This could be because brain cancers are most often diagnosed as a result of more advanced medical care or that there are other lifestyle issues that might be risk factors for cancer. Toxoplasma antibody rates may be higher in high GDP countries (possibly because more people own cats, or for a number of other reasons) and thus the statistics shown an association between brain cancer and Toxoplasma antibodies.  It does NOT mean that Toxoplasma infection is necessarily causing brain cancer.  As the authors say, "This leaves open the possibility that brain cancers and T. gondii are both affected by a third correlated factor."
  • This study included all brain tumours. It's hard to believe that Toxoplasma would be a risk factor for all of the various brain tumour types, if there is actually an association.
  • The Toxoplasma prevalence data weren't obtained in a standard manner by the researchers. Rather, they took data from a paper written in 2006. That paper obtained the data from various other published papers, some decades old. It doesn't mean that the data are not valid, but using data from studies that collected the information in different ways and from vastly different time periods creates some weaknesses.
  • Studies that are looking at a subject from a high level don't necessarily tell you what the risk is at the individual level. As the authors state "...analyses of data aggregated at the population level may not pertain to individual risk." (In epidemiology, this is called the ecological fallacy.)
  • A large percentage of the human population (~1/3) has antibodies to Toxoplasma, indicating previous infection. That's a huge number, yet the incidence of brain cancer is very low overall. Certainly, even if there is a true association, the likelihood of an individual developing cancer from Toxoplasma is very low.
  • Pet cats rarely shed Toxoplasma. They usually only shed for a couple of weeks of their life, typically when they're kittens. Also, the Toxoplama oocysts must live in the environment for 24 hours or longer to become infectious and a person has to ingest them to get infected. Therefore basic hygiene practices should reduce the chance of exposure even if a cat is shedding oocysts.

This is an example of a study that is great for generating questions that need to be answered, but not answering the questions. They've shown a crude association between toxoplasmosis and brain cancer. What that means is more detailed study is needed to see if the association is real (i.e. not the result of some other correlated factor) and furthermore to try to determine if the association is actually causative. Unfortunately, the press and internet don't understand that aspect and freak people out with statements such as "Cat parasite linked to brain cancer. A parasite spread by cats could almost double their owner's chance of developing brain cancer, research suggests."

One of the paper's concluding statements sums it up nicely: "Clearly, further research is necessary to determine the proximate links between T. gondii and different types of brain tumours and to investigate a mechanism of action." That means we need to work to determine what the true nature of the association is, and not panic at the possibilities.

Feral cats and bat-bite-badness

Sunday's Toronto Sun contained an article entitled "Woman's hand disfigured by cat attack" with the compulsory gross picture. The story is about Brenda Sims, who took in a feral cat, was then bitten by the cat, and then developed severe complications from the bite. The situation is a reminder of the potential problems encountered when dealing with feral animals (cats included) and complications that can occur from any cat bite.

Back in April, Ms. Sims took in a young male cat that she described as "five pounds of pure disease."  The cat, named Cheech, had been taken off the streets and was clearly not someone's lost pet. Cheech began following her around the house, growling and hissing. Not surprisingly, the well-meaning woman was eventually bitten. 

Ms. Sims has had multiple surgeries since then, including one that removed a large section of tissue from her hand and replaced it with some taken from her thigh. She's been largely unable to work since the injury and faces long term problems with function and appearance of her hand.

Ms. Sims is warning people about the dangers of feral cats. "It's like taking a tiger out of the jungle and into your home, and expecting it to be all good, and be a house cat..."

Dr. John Embil, Director of Infection Prevention and Control for the Winnipeg Regional Health Authority echoes her warning about feral cats, adding that feral cats can transmit rabies or severe bacterial infections such as Pasteurella multocida through bites. That's very true and a good reminder, but it perhaps overstates the importance of "feral." Any cat can carry Pasteurella multocida, along with many other problematic bacteria, in its mouth. A bite from any cat - domestic or feral - can cause serious infections. While an individual feral cat may be more likely to bite than am individual pet cat, most cat bites and cat bite infections are presumably from pet cats because people have more contact with them.

Dr. Embil highlights the problem with cat bites: "The concern we have with cat bites is that the teeth are very long, sharp and pointy. And those teeth can puncture deeply. You can get serious infections." Cat bites can be similar to injecting a bacterial cocktail deep into the tissues, not surprisingly resulting in infection in many cases.

Some take home messages:

  • Leave rescuing feral cats to people with experience.
  • If you want to rescue a cat, get it from a shelter, humane society or other reputable and experienced organization. They will have assessed the cat's behaviour and health status, which will decrease the chance that you'll get an aggressive and/or sick cat.
  • If a cat constantly stalks you around the house looking like it's going to attack (and not like it wants to play), it probably will attack and it shouldn't be in your house.
  • Any cat bite can cause severe complications. Every cat bite should be taken seriously and medical advice should be sought. Bites over the hands, feet, joints, tendons, genitals or in people with compromised immune systems typically require antibiotics to help prevent infection.

More information about cat bites can be found on the Worms & Germs Resources page.

Hendra virus in a dog

Adding a new twist to the already very concerning situation in Australia, Hendra virus infection has now also been identified in a dog. It's been a bad year for Hendra virus in Australia, with larger numbers of cases of this highly fatal disease in horses in a geographic range that seems to be expanding. Spread by flying foxes (fruit bats), Hendra virus predominantly infects horses, but can be transmitted to people working with infectedhorses.

The Australian Animal Health Laboratory in Geelong has now announced diagnosis of Hendra virus infection in a dog. The dog is from a quarantined farm in Queensland where the virus has been identified in a horse. The dog was healthy and was tested as part of a standard policy to test dogs and cats on infected farms. It's great to see this approach being used, since it helps identify other potential sources proactively - something that is often overlooked in outbreak investigations that focus only on the main species that are already known to be involved.

In this case, the dog had antibodies against the virus in its blood. That means that it was exposed to the virus and mounted an immune response. It doesn't indicate whether it was exposed recently or in the past. Two tests for the virus itself were negative, suggesting that the dog's immune system eliminated the virus (or that the virus isn't really capable of surviving for long in a dog). This is a good news/bad news scenario.

Bad news:

  • Dogs can be infected. It increases the range of known susceptible species.
  • If dogs can be infected and shed live virus, then they could be a source of infection for other individuals, including people.
  • The dog wasn't sick. This might sound like strange "bad news," but healthy carriers of infectious diseases are harder to spot and control than ones that are sick.

Good news:

  • The dog wasn't shedding the virus. That's critical since if dogs can be infected but not infectious (i.e. if they can carry the virus but not transmit it), then they are of limited concern.
  • They have been testing farm dogs and cats as a routine measure, and this was the first positive. Infection of pets therefore must be relatively uncommon even on farms where the virus is active.
  • The dog wasn't sick. While it's only one case and doesn't guarantee dogs won't be affected clinically, this might suggest that dogs just occasionally get exposed with no disease. Since it's highly fatal in other species, that's a good thing.

What should be done based on this?

  • Probably not much more than should have been done before this finding, but it's a good reminder about the potential involvement of other species.
  • Dogs and cats should be kept away from fruit bat roosting sites.
  • Dogs and cats should be kept away from infected horses.
  • If a farm is quarantined because of Hendra virus, dogs and cats should be tested and quarantined. Quarantining the animal while testing is underway helps reduce the risk of an infectious dog or cat (should that occur) transmiting the virus to people on the farm, or wandering away and exposing other people or animals.
  • Animals of any type in areas where Hendra virus is active that get sick with signs that could possibly be consistent with Hendra virus infection should be tested.

This should also be taken as yet another reminder that infectious diseases are unpredictable. Considering the potential involvement of different species in a proactive manner as was done here is critical.

Image: Bay Horse and White Dog by George Stubbs (1724-1806)

This Worms & Germs blog entry was originally posted on equIDblog on 26-Jul-11.

Staph food poisoning...possible pet reservoir

When it comes to public health concerns about staphylococcal bacteria from pets, most of the attention gets paid to methicillin-resistant strains like MRSA. That's not surprising considering how important MRSA is in human medicine. However, staph that aren't methicillin-resistant can also be a problem, since they can cause the same types of infections that resistant types can (they are just easier to treat). Another issue that often gets overlooked is staphylococcal food poisoning.

Staphylococcal food poisoning is one of the most common foodborne illnesses and results from growth of certain strains of staphylococci in poorly handled or stored foods. If staph get into food and the food is kept at improper temperatures, the bacteria can grow. If the strain of staph that's in the food is one that can produce enterotoxins, these toxins can accumulate in the food at high enough levels to cause food poisoning when eaten. In most cases, people are probably the origin of enterotoxin-producing staph that contaminate food, but pets are another possible source.

A recent study in Vector-borne and Zoonotic Diseases (Abdel-moein et al 2011) looked at enterotoxigenic staph in 70 dogs and 47 cats. Swabs were collected from the mouth, nose and wounds. Nasal swabs were also collected from 26 people. The researchers isolated enterotoxigenic Staphylococcus aureus (strains of S. aureus that possessed genes for enterotoxin production) from 10% of dogs and 2.1% of cats, as well as 7.7% of people. Most of the positive samples from pets were oral samples.

This study shows that dogs and cats can be potential sources of strains of S. aureus that cause food poisoning. Since the staph are often in the animals' mouths (and therefore presumably shed in saliva), animals can potentially contaminate food with these enterotoxigenic staph fairly easily, but it's unknown how often this occurs.

Prevention measures are pretty basic but should be considered, including:

Urinary tract infection treatments guidelines: Dogs and cats

Urinary tract disease is a common reason for use (and misuse) of antibiotics. In veterinary medicine, one thing that we lack is clear clinical guidelines (particularly regarding antimicrobial use) to help manage specific types of diseases. In human medicine, there are some excellent guidelines of this kind (e.g. the Infectious Disease Society of America guidelines) available for a range of diseases, and these can greatly assist with proper management of cases.

Because of the lack of veterinary guidelines, the International Society for Companion Animal Infectious Diseases has started a guideline development program. Using a committee of international experts in the fields of infectious diseases, internal medicine, microbiology and pharmacology, from both human and veterinary medicine, and extensive discussion, debate and revision, specific treatment guidelines are being developed for different types of infectious diseases. The first set, Antimicrobial Use Guidelines for Treatment of Urinary Tract Disease in Dogs and Cats, has now passed peer-review and the guidelines have been published in Veterinary Medicine International, an open-access journal available to all veterinarians.

To download the guidelines, you can also click here.

Giardia in dogs and cats in Ontario

Dr. Andrew Peregrine, a veterinary parasitologist at the Ontario Veterinary College, presented some data about the types of Giardia found in dogs and cats in Ontario at this week's University of Guelph Centre for Public Health and Zoonoses annual meeting.

A lot of attention has been paid to Giardia types in recent years. That's because, contrary to earlier thoughts, it's now known that certain types (also called assemblages) of Giardia can infect multiple species while others are host specific (i.e. they only infect one species). This is very important because if a dog or cat is shedding Giardia in their stool, the type determines whether there is any risk to people.

In the Ontario study, 75 canine and 13 feline Giardia-positive fecal samples were typed. In canine samples, assemblage D accounted for 68% of samples, while assemblage C accounted for 31%. These two are dog-specific, meaning 99% of typed canine samples contained only dog-specific types and were therefore no risk to human health. The other sample contained assemblage B, a zoonotic type that infects humans and animals. In contrast, 13/13 of the feline samples were assemblage A, a zoonotic type of Giardia.

These recent Ontario data indicate a low risk of transmission of Giardia from dogs to people, but some risk from cats - at least in Ontario. It's important to note that there appears to be geographic variation in this trend. Other recent studies have reported similar results, with the predominance of dog-specific types in dogs. However, a few studies have shown a predominance of the zoonotic assemblage A in dogs. These have mainly been in low socioeconomic status areas with infrastructure challenges that could increase the chance of dogs being exposed to human feces. Therefore, it may be that in areas where there is good sanitation, dogs are most likely to get Giardia from other dogs. When there are sanitation challenges, dogs may be more likely to be exposed to human types. So, it's important to know trends in different geographic regions to understand the risk of transmission from pets to humans.

Newmarket OSPCA ringworm "outbreak" investigation report

As many of you know, there was a large ringworm "outbreak" at the Newmarket (Ontario) OSPCA shelter in 2010 that led to a public outcry in response to plans to depopulate the shelter. In the aftermath of the event, an independent investigation was launched, headed by Mr. Patrick LeSage (former Chief Justice of the Ontario Superior Court) and Dr. Alan Meek (former Dean of the Ontario Veterinary College). The investigation involved a comprehensive examination of activities pertaining to the outbreak and shelter operations, in conjunction with relevant experts (disclosure: I was one of those).

The report of the investigation is now available, and covers important aspects such as whether an outbreak was actually present (short answer: no) and whether there were major problems in shelter operation (short answer: yes). Most importantly, it provides a comprehensive set of recommendations to improve the operations of the Newmarket shelter and OSPCA as a whole.

The report, in its entirety, was released today by the OSPCA and is available for download on their website. The report is on the site in multiple files: the main report is listed as "Index" and contains the ~90 page overview and recommendations. The expert reports, which might also be of interest, are tables D1-3, E, F and G.

Rabies in person in California

Although limited on information, there's a recent report of a person with rabies in California, with some hope for survival. Rabies was apparently diagnosed in the person on May 6. Incredibly, not only is the woman alive, but she is reported to be in "stable condition" and improving at UC Davis Medical Center. That's remarkable because rabies is almost always fatal, and death usually occurs fairly quickly by the time rabies is suspected and diagnosed. Rabies survival has been reported but is extremely rare.

While it's far too early to talk about survival and cure of the woman's illness, there are many different factors that could be involved in this potentially successful treatment.  These include very rapid administration of anti-rabies treatment, use of the "Milwaukee protocol" (which was the first successful treatment protocol for rabies in a person, which has also failed to be successful numerous times since), pre-existing partial immunity from previous vaccination, and/or the whims of biology and the immune system. Hopefully, this person will continue to improve and more information will be made available about why treatment has been successful so far.

The source of rabies is suspected to have been feral cats, although this is far from certain and it may be that this presumption is based on the lack of other more likely possibilities. While this is an encouraging report, it doesn't change the fact that rabies almost always kills, and it's almost 100% preventable with proper post-exposure treatment. People need to be aware of how to avoid rabies and that prompt treatment is needed anytime rabies might have been encountered.

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MRSP transmission between people and pets

Today (like most days) I answered questions about the potential for transmission of methicillin-resistant Staphylococcus pseudintermedius (MRSP) between people and pets. We have a long way to go before we fully understand the issues, but research continues to progress and we're learning more and more. A recent study by Dr. Engeline van Duijkeren and colleagues from Utrecht University published in Veterinary Microbiology (van Duijkeren et al. 2011) steps up our knowledge another notch.

In their study, the authors enrolled 20 households that owned pets with MRSP infections. They went into the households and collected samples from the index pet (the one with the MRSP infection), other pets, people and the household environment.  At the time of sampling, 10 of the infected pets had gotten over their illness while the other 10 still had active infections.

Some highlights of the study:

  • 4/14 (36%) of other dogs and 4/13 (31%) other cats in the households were MRSP carriers. In households where the pet still had an active infection, an astounding 86% of the other animals were carriers. All these numbers are much higher than the expected baseline rate of MRSP carriage by healthy pets in households, giving strong support to the notion that MRSP is being passed between pets in households with an infected pet.  From an infection control standpoint, it's probably reasonable to assume that a pet living with an infected animal is a carrier.
  • MRSP was isolated from 2/45 (4%) of nasal swabs from people. This is not too surprising, since we know that MRSP (and its susceptible counterpart, methicillin-susceptible S. pseudintermedius (MSSP)) can be transmitted between people and pets. This study shows us, however, that even when there is apparent MRSP transmission going on between pets in the household, it doesn't seem to commonly involve people.
  • MRSP was found in the environment in 70% of houses (and 90% of household where the pet was still infected). These are pretty big numbers but are not really unexpected, since if MRSP is in and/or on animals, it's bound to be found in the environment. Whether the environment is a potential source of human or animal infection isn't known, but it's something to consider.

This research gives more evidence that MRSP can be spread readily between animals but less so between animals and people. It could be because animals have closer contact with each other in a household than with people, but a bigger factor is probably that S. pseudintermedius is more adapted to living on animals than on people.

MRSP info sheet update

The ever-popular methicilin-resistant Staphylococcus pseudintermedius (MRSP) owner information sheet has been updated and can be found, along with info sheets on many other topics, on the Worms & Germs Resources page.

Travel, pets and infectious disease risks






What to do?


Animal first aid kit recall

Earlier this year, there was a large recall of pre-packaged alcohol wipes made by Triad Group because of bacterial contamination and implication of the wipes in a large number of human infections. While alcohol is used as an antiseptic, bacterial spores are inherently resistant to the effects of alcohol and contamination with spore-forming bacteria can turn wipes into disease vectors. In the latest outbreak, alcohol wipes were contaminated with Bacillus cereus and implicated in the deaths of 7 people.

As an extension of the earlier recall, Creative Pet Products and MAI/Genesis (Veterinary Concepts) have recalled first aid kits marketed for use in pets and horses. In addition to the potential for contaminated alcohol wipes there is concern that the "sterile" lubricant jelly may not be so sterile, and could also be contaminated with Bacillus cereus. Additionally there is mention that the iodine pads could be contaminated with another bacterium, Elizabethkingia meningoseptica. (It sounds like they have some pretty major quality control issues. Not surprisingly, production at the plant has been suspended pending an ongoing FDA investigation.)

Anyway, anyone with one of these first aid kits should check to see if their kit is involved in the recall:

Alcohol prep pads – Kits affected:
10140 Horse Aid™ Kit
10145 Sporting Dog Kit
10148 Sporting Dog II Kit
10151 K9 First Aid Police & Military Kit
Brands: Triad or NovaPlus
All Lot Numbers

Iodine prep pads – Kits affected:
10140 Horse Aid™ Kit
10145 Sporting Dog Kit
10148 Sporting Dog II Kit
Brands: Triad or H&P Industries
Lot Numbers starting with 8, 9, 0, 1

The kits were distributed in the United States, Australia, the United Kingdom, Taiwan and Costa Rica.

If you have one of these kits, you should get rid of the affected items. For further details (and presumably how to get a refund) click here.

This Worms & Germs blog entry was originally posted on equIDblog on 09-May-11.

Can dogs spread Valley Fever?

I received this question yesterday, pertaining to a potential therapy dog.

Valley Fever, also known as coccidioidomycosis, is a fungal infection caused by Coccidioides immitis or Coccidioides posadasi. These fungi live in the soil and are most common in the southwestern US, northern Mexico, and parts of Central and South America. They are part of an unusual group of fungi called "dimorphic fungi," meaning they exist in two forms. One form in found in the environment (soil). This arthroconidial form is the infectious form. The other yeast-like form is present in the body tissues during infection, but is not (or at least is very minimally) transmissible.

Disease from Valley Fever is rare in healthy people.  These fungi are mainly a concern in people with compromised immune systems. When illness occurs, flu-like disease, respiratory disease, rash and joint pain are the most common signs, but disseminated infection (i.e. infection throughout the body) is a much more serious form of the disease that can occur.

Valley Fever is similar in dogs, with most dogs have mild to inapparent disease, and most sick dogs having vague signs and respiratory disease. Cats often develop skin lesion. Disseminated disease can also occur.

While coccidioidomycosis can occur in both humans and animals, the risk of transmission between humans and animals is extremely low. The fact that it occurs in both humans and animals is because both humans and animals get exposed to the same sources, not because they spread it between each other.

However, there is a slight risk that shouldn't be ignored. There are two situations that are of concern.

  • Bites: There is one report of a bite-associated infection in a veterinary technician. The risk of infection after a bite from an infected animal isn't known, but anyone bitten by an infected animal should seek medical advice. Presumably, nothing would be done initially but there could be close monitoring for disease so that it can be treated early if problems develop.
  • Veterinary procedures: Infection has been reported in a person performing a necropsy (autopsy) on an infected horse. It was thought that infectious endospores were aerosolized when an infected area was cut with a saw as part of the procedure, and inhalation of the fungus lead to disease.

There's also a theoretical concern with handling bandage material from infected animals. While the active infection would be caused by the minimally infectious tissue form of the fungus, it's possible that infectious arthroconidia could develop in a bandage.

People with infected pets have little about which to be concerned. The main risk (which is also very low) is infection from a bite from an animal with disseminated disease. Basic bite avoidance should minimize this risk, however medical care should be sought following any bite and people at high risk of serious infection (e.g. people with compromised immune systems) should take particular care when interacting with infected animals. If a pet owner has to change a bandage on an infected animal, they should wear gloves, double bag and immediately dispose of the bandage, avoid contamination of the environment during bandage changing and thoroughly wash their hands after completing the task.

Image: The infectious arthroconidia of Coccidioides immitis (source: CDC Public Health Image Library #476).

Plague in New Mexico cat and dog

Plague has been identified in a dog and cat from New Mexico. It’s not surprising, since plague is present in some wild animal populations in that region, but it’s still noteworthy because of the serious nature of the disease and the potential for transmission to humans.

Plague is a bacterial infection caused by Yersinia pestis. It’s carried mostly be certain types of rodents in different regions of the world, including parts of the southwestern US. It’s usually spread by fleas that bite an infected rodent and then bite a person or other animal, but it can also be spread by close contact with an infected animal. Cases in cats and dogs are uncommon, but occur in areas where plague is present in rodents, when pets have contact with infected fleas or close encounters with infected rodents (or rodent carcasses).


The latest two cases were in Santa Fe and Rio Arriba Counties in New Mexico. No details were provided about the form of plague (e.g. bubonic, pneumonic), the suspected source of infection or whether there is concern about human exposure. Finding plague in a pet is a concern for a few reasons. It indicates that plague is present in wildlife in the area, and people could be exposed from the same sources as the pets (i.e. fleas, contact with live or dead wildlife). Also, transmission of plague from pets to their caretakers can occur, particularly from cats with pneumonic plague (respiratory tract infection). Knowing that a person has had contact with a pet with plague is critical to making a prompt diagnosis. According to the World Health Organization, plague continues to infect more than 2000 people every year.

The New Mexico Department of Health has made the following recommendations:

  • Sick pets should be examined promptly by a veterinarian.

 Photo: The vector of Yersina pestis: a flea (click image for source)

More on vets and MRSA

There are a number of published studies regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage by veterinarians, most reporting high rates compared to the general population. This is a concern because MRSA is an important cause of disease in both people and animals. Just having MRSA living in your nose doesn't mean you're going to get sick. Indeed, around 2-3% of normal, healthy people are likely carrying MRSA at this moment. However, if you are carrying MRSA, you are at increased risk of developing an infection under certain circumstances. In veterinarians MRSA carriage is also a concern because of the potential for transmission to patients (and potentially from those patients back to people).

A recent Australian study in the Australian Veterinary Journal (Jordan et al 2011) looked at MRSA carriage in different types of veterinarians. The rates were:

  • 0.9% in industry and government veterinarians (who have limited contact with animals)
  • 4.9% in small animals veterinarians
  • 11.8% in veterinarians with horses as a major component of their caseload
  • 21.5% in equine veterinarians

These results are similar to some of our earlier studies, with carriage rates in small animal veterinarians being  higher than would be expected for the general population, and carriage rates in equine veterinarians being very high.

Why do veterinarians have high rates of MRSA carriage?

There's no definitive answer but there are some likely causes. Veterinarians have contact with large numbers of pets and horses, and we know these animals can carry MRSA. Even if the percentage of dogs, cats or horses carrying MRSA is very low, when you multiply that by the number of animals a veterinarian touches every week, you can see how contact with an MRSA-carrier is pretty likely. Veterinarians also tend to have close contact with sites where MRSA can be found, such as the nose. This makes the chance of having contact with the bacterium itself more likely. An additional issue the often sub-optimal use of routine infection control and hygiene practices (especially hand hygiene), which may also increase the risk of MRSA transmission. Put all these together, and it makes sense that veterinary personnel are at increased risk.

Why do carriage rates tend to be higher in equine veterinarians?

It could be because MRSA is more common in horses than small companion animals. Another plausible explanation is the fact that the horse's nose (the most likely site for MRSA to be living) is commonly touched during examination and restraint, and horses have pretty big noses to start. Additionally, good hygiene can take more effort on some farms, as sinks and often even hand sanitizer are not as readily available as they are in a clinic.

More information about MRSA in companion animals can be found on the Worms & Germs Resources page.  More information about MRSA in horses can be found on our sister site, on the equIDblog Resources page.

(click image for source)

This Worms & Germs blog entry was originally posted on equIDblog on 19-Apr-11.

The dog in your bed probably won't kill you

A month or two ago, there was a lot of press about the risks of pets sleeping in beds. It was in response to an article in the journal Emerging Infectious Diseases that didn't put forth any new information, but summarized a few diseases that could potentially be transmitted by pets. Unfortunately, the relative risk of those diseases wasn't really explored, and some media reports latched onto diseases like the plague, transmission of which can occur between pets and humans but the likelihood of this in most areas is essentially nil.

Anyway, an article at has taken a more balanced approach towards the subject. One sentence perhaps say it best: "Many of those scare headlines, however, missed the main point of Chomel’s work: For most people, the risks are minimal, and there are easy ways to go about preventing pet-to-owner disease sharing."

I won't go into details here, since you can read the article yourself, but a key component is that pet ownership is never no-risk, but is usually low-risk. Basic hygiene practices and common sense can reduce the risks further. The cost-benefit needs to be considered, and while we can never completely eliminate the "cost" aspect, the benefits of pet ownership certainly outweigh the costs in the vast majority of households.

Vets sued over MRSA

When I give presentations to veterinarians about infection control, I often talk about legal liability as one reason they need a good infection control program. I talk about the potential bad scenarios, such as someone getting an MRSA infection from an animal and then turning around and suing the vet. I usually say something like "I don't think it's happened yet, but you never want to be an index case". I may need to change that line now that a Texas veterinary clinic is being sued over a person's MRSA infection.

However, the lawsuit, filed April 4, isn't from an owner. Rather, it's from a veterinary assistant. The woman is suing the clinic, claiming they were negligent because they didn't warn her that she would be caring for an MRSA-infected animal. She claims that she contracted the infection on the job and that it "has physically impaired her for the rest of her life."

I know nothing about this case beyond what's in the link above, however it raises a few important issues and questions.

What does this mean for the veterinary clinic?

  • I've been saying for years that the bar is being raised and clinics need a good infection control program, including training and education, to reduce infections of both pets and people.
  • As awareness of zoonotic diseases and veterinary infection control increases, the potential for lawsuits may similarly increase.

What level of warning is required for veterinary employees?

  • This varies with the type of person.
  • A veterinarian shouldn't need to be informed that they will work with animals carrying zoonotic pathogens. If they didn't pick that up in vet school, they've got some other major issues.
  • A veterinary technician should have a similar understanding of the risks and measures that should be undertaken to reduce those risks.
  • Lay personnel are a different story. You can't assume a lay employee has any knowledge whatsoever about infectious diseases, zoonotic diseases or infection control.
  • If there are minors in the clinic (e.g. co-op students, volunteers), you need to go even farther, and there should be written notification of parents of the risks, and measures that are taken to reduce the risks.
  • In general, the less the veterinary education, the greater the need for clear and documented education about disease avoidance.

How do you prove this person acquired MRSA on the job?

  • That's tough. Perhaps there was a clear link with a case. Even stronger would be showing that the human and animal MRSA strains were the same, but that's unlikely to have been done. Just because MRSA can be found in animals doesn't mean that MRSA infections all come from animals. Humans are thought to be the source of the vast majority of MRSA infections and pets, and while pets can potentially spread it back to people, this is ultimately a human disease. People pick up MRSA all the time in the general population, although the percentage  of people who carry it at any given time is still low.
  • MRSA carriage rates have been shown to be higher in veterinarians than in the general public in a few different studies. I think it's clear that MRSA exposure is a risk of veterinary practice. However, proving that an individual infection came from a pet in a clinic is still difficult.

How can vet clinics reduce the risk of MRSA (and other) infections, as well as lawsuits?

  • Have an infection control program in place.
  • Make sure infection control practices and policies are written down.
  • Make sure all employees are appropriately trained and document the training.
  • Make sure people follow all of the required protocols.

Infection control isn't rocket science. At its heart, it's the application of some very basic practices. Infection control hasn't had a high profile in companion animal veterinary medicine in the past, but things are changing (albeit slowly). Available resources can help veterinary clinics implement a decent infection control program with minimal effort. A good resource is the document Infection Prevention and Control Best Practices for Small Animal Veterinary Clinics, which is available (free) for download on the Worms & Germs Resources page.

Treat the pet, not the lab result

The title of this post describes a very basic concept, but one that is sometimes forgotten or hard to follow. The key point is that the goal of treating a sick pet is to make the pet well. Getting well and getting "normal" laboratory data aren't necessarily the same thing.

A question that comes up a lot with MRSA, MRSP and other bacterial infections is "should my pet be tested after treatment to see if the bug is gone?" The answer is usually "no."

One reason to not re-test is just what I said above. The goal of treatment is to make the patient healthy. That doesn't necessarily mean that MRSA, MRSP or whatever bug is causing the problem needs to disappear. In fact, the bacterium that causes a given infection often remains (in smaller numbers) in or on the body somewhere. If it's a skin infection, the bacterium may still be present on the skin where the infection was. However, if the body is handling it well, then it's not necessarily a problem. We have to remember that every animal (and person) has multiple types of bacteria in or on it that can cause disease given the right circumstances. We're never going to eliminate them all. In fact, trying to get rid of all potentially bad bacteria would probably result in bigger problems.

Another concept that I emphasize a lot is only do a test if you have a plan for using the result. If you don't have a clear reason to do the test, and if the result won't impact your decisions or provide information you need in the future, then why do it? While a negative culture might be nice to see, it's not necessarily a guarantee that a particular bug is gone. Furthermore, a positive culture doesn't lead to actions that are any different from those that would be taken if the culture is negative in most situations because, as mentioned above, we're looking for clinical cure (getting better) rather than microbiological cure (getting rid of the bug). Rarely would we extend treatment or do anything different in response to a positive culture in a healthy animal.

The bottom line is post-treatment cultures are rarely needed. There may be some circumstances where testing after treatment is useful and where the results would lead to a defined plan of action, but these are few and far between.

Image: A Mueller-Hinton agar culture plate being used to test the antibiotic susceptibility of a bacterial isolate according to the Kirby-Bauer method. (source: CDC Public Health Image Library #10785)

Dead birds around a feeder: What to do?

Like any animal, disease outbreaks can occur in wild birds. Unless they are large outbreaks they often go unnoticed, but smaller outbreaks can sometimes be encountered by homeowners with bird feeders. Because bird feeders are mixing sites for birds, they are also sites of disease transmission and a place where deaths can be identified. In an outbreak, feeders can contribute to the spread of  infection between birds, and potentially be a source of infection for people or pets.

A classic example of this is Salmonella infection in songbirds. Outbreaks occur periodically and are often identified by people with bird feeders who start to find the odd dead bird in their yard. Some birds can be healthy carriers of the Salmonella bacterium (and therefore be a source of infection for others), while other birds may get sick and potentially die from the infection. If you have noted dead birds around a bird feeder, consider the potential for a disease outbreak, particularly salmonellosis.

The risk to people and pets from Salmonella outbreaks in birds is reasonably low, and probably greatest in cats. Most reports of songbird-associated salmonellosis (songbird fever) are in cats, because cats are more likely to catch and eat songbirds. Sick birds are easier to catch, further increasing the likelihood of exposure during an outbreak. Exposure is also possible through scavenging already-dead birds and perhaps from exposure to heavily contaminated surfaces or spilled feed around feeders.

General recommendations during an outbreak of salmonellosis in songbirds include:

  • Keep cats indoors. This is a good idea at any time, but if you have an indoor-outdoor cat, keep it indoors if there might be an outbreak underway.
  • If your pet has been exposed to a sick bird or an area where sick or dead birds have been found, and your pet gets sick, make sure you tell your veterinarian about the birds.
  • Clean the bird feeder and then disinfect it by soaking it in 10% bleach for 30 minutes. Rinse it after the bleach treatment. If the feeder is difficult to properly disinfect (or you don't want to try), get rid of it by double bagging it and putting it in the garbage.
  • When cleaning the feeder, do it outside so that you don't contaminate any household surfaces. When handling the feeder, wear disposable gloves and wash your hands after you remove the gloves.
  • Keep the feeder down for 1-4 weeks. This reduces the concentration of birds in the area and may help reduce mingling of sick and healthy birds.
  • Remove any dead birds by burying them at least two feet deep in a flowerbed (not in a vegetable garden!).  This is not very easy or practical however - alternatively, double bag the bodies and put them in the garbage, avoiding direct contact with the birds and washing your hands afterward.

I have MRSA...should my pet be tested?

I get this question a lot, from both pet owners and veterinarians. Typically, my answer is "no."

Why not?

  • The two big questions I always ask are "why do you want to know and what would you do with the results?"

Sometimes people want to know their pet's MRSA status to see if the pet was the source of their infection.

  • However, MRSA in pets is typically associated with MRSA in humans, i.e. if a pet is carrying MRSA, it probably got it from the owner or another close contact. Finding MRSA in a pet after someone is diagnosed with an MRSA infection doesn't mean the pet was the source. More likely, the person got MRSA somewhere else and passed it on to their pet.


  • Carrying MRSA presumably increases the risk of an MRSA infection, but likely only in animals already at risk of an infection because of underlying disease or other risk factors such as surgery. The risk to the average pet from short-term MRSA colonization is probably limited. Also, if the pet was identified as a carrier, we wouldn't be doing anything to eliminate carriage, since we have no idea if decolonization therapy is effective in animals, and it doesn't seem to be needed (because dogs and cats almost always get rid of it on their own). Therefore, it's hard to justify screening for this reason. If the animal was getting ready to undergo surgery, then that might change my answer.

For me, it's also very important to consider what you'd do with the results of any test. In general, in a household where a person has an MRSA infection:

If the pet tests negative, I'd say that it doesn't 100% guarantee that the pet is truly negative, since no screening test is absolutely 100% sensitive. Also, the test only tells you the status of the pet at the time of sampling. It could have picked up MRSA five minutes after the swabs were taken. So, a negative result means the animal is probably negative. Since it's not absolutely negative and since the pet would be at risk of picking up MRSA from the infected person after it was tested, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose) to reduce the chance of the pet becoming colonized and to reduce the risk of MRSA transmission from pet to person if the pet was actually a carrier.

If the pet tests positive, I'd say that we certainly couldn't say the pet was the source of infection. More likely, it got it from the person with the infection. Since we know that MRSA carriage in dogs and cats is almost always transient, and that they will almost always get rid of it on their own if re-exposure is prevented, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose).

Since my response to either result would essentially be the same, why test?

Efforts are better spent on good household hygiene practices and restricting contact with high risk sites. On both pets and people, this would include the nose, as well as any sites that are infected or sites that are prone to infection (e.g. skin lesions). That's going to be much more worthwhile and rewarding than testing the pet.

Rabies update

ProMedMail tends to publish a monthly rabies report. While a lot of it involves the same basic issues, there are sometimes a few more interesting stories:

Rabies in a donkey in Georgia

  • Like all mammals, donkeys are susceptible to rabies virus but infections are not particularly common. Raccoon rabies has also be identified in the area, and a bite from a raccoon may have been the source.

Bite from a rabid kitten in Pennsylvania

  • A York County woman was bitten by a kitten that ran into her house when the door was opened for someone else. The kitten bit her when she grabbed it to throw it (hopefully not violently) back outside... an understandable reaction but not what you want to do in a case like this. You need to know whether a wild animal that bites is rabid, and if it gets away, you can't test it. You need to get away from it but keep it contained until someone can come get it. The other problem with people getting rid of the animal is that they might not recognize the risk of rabies. In this case, the kitten was hit by a car after being removed from the house, which allowed for it to be tested.

Yet another report of a dog being exposed to rabies through contact with wildlife, then being euthanized because it was not properly vaccinated.

  • An unvaccinated animal that has been exposed to a rabid animal has to be euthanized or undergo a strict six-month quarantine. A vaccinated animal only needs a 45-day observation at home.

Rabid bobcat attack in Florida

  • Encountering a manic bobcat isn't something I'd like to do, and a LaCrosse, Florida woman spent nine days in hospital after being attacked by one. The 25-pound cat was trying to get the family's cat, then lunged at the woman when she came outside the house, aiming for her neck. Her husband then shot it. They knew that the bobcat needed to be examined, and took the rather unusual approach of bringing it to the hospital emergency room with them (I'd love to have seen that). I don't imagine hospital personnel did anything, but Florida Fish and Wildlife Conservation Commission personnel came and got it, and later confirmed that it was rabid. (Image: Lynx rufus, US Fish & Wildlife Service)

Plague in Oregon


Here are highlights of the CDC report (in italics) with some extra comments.

Plague, caused by Yersinia pestis, is enzootic (present in the population, typically at a low level) among rodents in the western United States. Humans can be infected through 1) the bite of an infected flea carried by a rodent or, rarely, other animals, 2) direct contact with contaminated tissues, or 3) in rare cases, inhalation of respiratory secretions from infected persons or animals. In September 2010, the Oregon Health Authority reported the first two cases of human plague in Oregon since 1995 and the only two U.S. cases in 2010.


...25 days after specimen collection, the isolate was identified as Y. pestis... Both patients recovered uneventfully after empiric therapy with doxycycline and amoxicillin clavulanate potassium, respectively, although the latter is not considered effective in treating plague.


Sleeping in the same bed with dogs has been associated with plague in enzootic areas.  Plague patients with no history of exposure to rodents can be infected by Y. pestis if their pets carry infected rodent fleas into the home. Veterinarians always should recommend flea control to dog and cat owners.

This is an example of a situation where pets can play a role in human infection while not being the direct source of infection. While direct pet-human transmission can occur, this typically involves situations where someone has close contact with a pet that is sick with the plague. Most often, this kind of transmission is associated with close contact with cats with pneumonic (respiratory) plague.

Key aspects of reducing the risk of pet-associated plague in areas where plague is, or may be, present, are:

  • Preventing contact of pets with wildlife, living or dead.
  • Preventing roaming of pets in the wild.
  • Discouraging wildlife from living in or around homes.
  • Keeping cats indoors.
  • Routine flea control.

More information on plague and pets is available in our archives.

2010 Animal Rabies Summary

In Canada, rabies testing and surveillance is performed by the Canadian Food Inspection Agency (CFIA). National data for 2010 are now available and indicate there were a small number of cases in domestic animals, with more in wildlife, for a total of 123 cases.

Dogs: There were three cases, all in Saskatchewan.

Cats: Four cases, three in Manitoba and one in Alberta.

Horses: One rabid horse in Manitoba.

Cattle: One, from Manitoba.

Skunks: 60 cases, 33 in Manitoba, 17 in Saskatchewan and 10 in Ontario.

Bats: 48 rabid bats, most in Ontario (29) but also in BC, Alberta, Saskatchewan, Manitoba, Quebec, New Brunswick and Nova Scotia.

Foxes: Six from the Northwest Territories or Nunavut.

No rabid sheep, goats, raccoons (down from 58 in 2007), wolves or other species.

Manitoba seems to win the 2010 rabies prize, while Newfoundland and Labrador, Prince Edward Island and the Yukon had no cases.

As with any disease surveillance, these numbers underestimate the scope of rabies. For an animal to appear on the list, rabies had to be considered and testing performed. So, for  wildlife, it's a massive underestimation of the number of cases, since most affected wildlife don't get tested. Wildlife testing (and testing in general) is typically only done when there has been the potential for human exposure. Domestic animal cases are probably a fairly close representation of the status of rabies in pet and farm animals, since it's reasonably likely that a domestic animal with rabies would be identified as such and tested (although certainly cases can be missed or neglected). As with wildlife, there is probably an under-identification of rabies in feral/stray dogs and cats, since testing would only be done on these animals if they are caught and if there was potential human exposure.

Lions and tigers and glanders

Glanders, a very serious disease of horses, donkeys and mules caused by infection with the bacterium Burkholderia mallei, has made the news again in a rather unusual manner – it has been reported as the cause of an outbreak in lions and a tiger at an Iranian zoo in Tehran.

The story goes that two Amur tigers arrived at the Tehran zoo from Eastern Russia in April 2010 as part of an exchange program between the two countries. The tigers were supposed to be used to help restore the tiger population in northern Iran on the Miankaleh nature reserve, but their living quarters there were apparently still not ready, and thus they were being kept at the zoo. One of the tigers died in December 2010.

And that’s were the story starts to get a little dicey. The Iranians claim the tigers were imported already carrying the disease, and that the last case of glanders at the zoo was 50 years ago. The tigers had already been at the zoo for eight months - although the incubation period for glanders can be months in some cases, it is normally only weeks. The Russians of course insist that the tigers were completely healthy when they were transferred – they’d been thoroughly examined and quarantined prior to being moved. (This makes the most sense to me, since transporting an animal such a long distance is a major stress and increases the risk of illness, and transporting an animal that is already sick would be even more risky. Not a chance I would take with two members of a species of which there are fewer than 900 individuals left in the world.) They also pointed out that a sick tiger from the cold regions of Russia would be much more likely to succumb to illness during the very hot Iranian summer, not during the winter.

Another report said that three lions at the zoo also died from glanders in the last two months, and subsequently another 14 lions were diagnosed with the disease, all of which were put down by the authorities. The main concern seemed to be the spread of the disease from the big cats to the feral cat population, and then to the human population. This second report states that “the tiger died after being fed contaminated meat, though it is possible it could also be related to the glanders.”  Yet another report said that the tiger was infected with feline immunodeficiency virus (FIV - the feline equivalent of HIV).

Facts to keep in mind:

  • Glanders is an highly contagious disease, and highly fatal (B. mallei is even classified as a Class B bioterrorism agent).
  • Animals that do recover from the disease can become long-term carriers of B. mallei, and are a risk to other animals (and people). Prompt euthanasia of affected animals is therefore often the primary means of controlling outbreaks (but the bacterium is susceptible to antibiotics).
  • The infection can be transmitted to other animals (and people), usually through close direct contact or contact with oral and nasal secretions and discharge from skin ulcers. It can also be transmitted by eating tissues from infected animals.
  • The bacterium is killed by most disinfectants, and UV radiation (sunlight).

Glanders can affect species other than equids, including people and cats, however there is very little information available about glanders in any felids, let alone lions and tigers. Theoretically it might be possible for the disease to spread from the zoo animals to feral cats and then to people, but I don’t know how many feral cats are brave (or stupid) enough to wander into a lion enclosure. There’s also a possibility that a glanders-positive feral cat may have infected the zoo cats (but again, it would have to be very brave, or very stupid). It is also unclear what tests were used to confirm that the big cats were infected with glanders, and it is unknown if other animals at the zoo have been tested. Since this is typically a disease of equids (and has also been found in goats and camels), I would certainly be checking these animals first.

The big question is, where did the glanders come from in the first place? It seems unlikely that the tigers brought it from Russia, when the disease is actually endemic in Iran (even though they’d had no diagnosed cases at the zoo for many years). Is there a carrier animal in the zoo? Were the animals infected by eating contaminated meat? Was it brought in by feral cats?  The source needs to be identified and addressed or animals will continue to be infected, which is particularly bad news for the kinds of rare species that may be found in a zoological collection. Some more details about the testing would also be appreciated – given the severity of this disease, and the severity of the consequences for positive animals (euthanasia), one needs to be as sure as possible that these animals are infected with B. mallei and not something else.

Photo: Amur Tiger (Panthera tigris ssp. altaica) (click image for source)

Miami Beach's Cat Poop Map






Image source:

No good deed goes unpunished: Cat rabies version

A Royal Oak, Michigan resident is undergoing rabies post-exposure prophylaxis after being bitten by a rabid cat. The person found a sick cat by the side of the road and took it to a vet clinic... a good deed in theory, but problematic in many ways. One obvious risk is the potential for rabies exposure, as occurred here. The cat was subsequently diagnosed as rabid, and having been bitten the good samaritan was clearly exposed. Fortunately, the veterinarian kept the contact information for the person who dropped off the cat, who can therefore now receive the necessary treatment.

Associated with this event, the Royal Oak Animal Shelter has issued the following reminder:

  1. Do not approach any animal if it appears sick. Call the Police to get animal control involved.
  2. Tell your children to stay away from any stray animals, whether they are skunks, dogs, or cats. Any of these could be infected.
  3. Vaccinate your dogs for rabies. It is the law.
  4. If you let your cats outside, STOP doing so. If you can't stop, please make sure your cats are vaccinated for rabies.
  5. If they already have been vaccinated, talk to your veterinary professional about having a booster administered to protect your animal. There is no cure for this deadly disease.

(click image for source)

Tuberculosis in pets: The treatment quandry

A few days ago, I wrote about tuberculosis (TB) exposure in several people who performed a necropsy on an infected dog. As part of that investigation, a cat in the household was tested and was also positive for TB. It was euthanized because of the public health concerns. A logical question from a reader was "Is there no treatment for animals, as there is with humans?"

Diagnosis of tuberculosis in an animal often results in prompt euthanasia, and some individuals and groups have euthanasia as a standard recommendation.


  • We have no data about how to properly treat an infected animal.
  • We have no data about how effective (or ineffective) treatment may be.
  • It's not easy to test animals before or during treatment to see if they are shedding the TB bacterium (Mycobacterium tuberculosis).
  • It's such a concerning disease in people that the inclination is to err on the side of caution when it comes to public health.

Is it an appropriate response?

In some circumstances, it probably is. In other circumstances, treatment shouldn't necessarily be dismissed. A major problem is the knowledge gap.

  • We don't know whether infected animals pose any risk to people. Human-animal transmission can occur, but it's unclear whether animals can transmit the infection back to people.
  • If transmission between pets and people occurs, we don't know what circumstances are involved. TB is not readily transmitted even between people. Short term exposure is not a major concern. It's likely that close and prolonged contact is required for transmission from pets, but we don't know for sure.
  • We don't know if certain infected animals are higher risk than others, although there probably are differences. A dog with respiratory TB and active disease is probably a much higher risk than a dog with a localized TB abscess.
  • We don't have easy and accurate ways to test pets for TB exposure and shedding. In people, sputum cultures are tested by having people spit in a cup. Getting a sample like that is obviously difficult in dogs. Collecting a good sample for testing is much more involved in pets and not amenable to routine testing (for research or monitoring).
  • We don't know for how long to treat a pet with TB, or which drugs are optimal for use.

Treatment might be reasonable when there is an animal with mild disease (or no signs of disease), when the animal was infected from a household contact (meaning that some degree of TB exposure has already occurred in the household and the dog would probably only be a secondary source of exposure), when there are committed owners who are willing to embark on time consuming and expensive treatment, when owners are able to keep the dog away from other animals and people during the treatment period, and when there is an understanding that treatment may not work.

When might treatment not be a good idea?

  • When the animal is shedding the TB bacterium in respiratory secretions.
  • When the owners cannot afford prolonged and expensive treatment and monitoring.
  • When the owners cannot be relied on the administer every dose of medication and make every required follow-up appointment.
  • When owners cannot be relied on to keep the dog away from other dogs and animals (and people) during the treatment period (or at least during the initial period).
  • When there are high-risk people in the household, such as people with HIV.
  • When serious disease is present, such that the chances of recovery are low.

Rabies vaccine failure in dogs and cats

A recent paper about rabies post-exposure treatment in animals (Wilson et al, J Am Vet Med Assoc 2010) also contained some interesting information about rabies vaccine failure in pets. The study, which looked at data from more than 1000 animals in Texas from 2000-2009, mentioned a vaccinated 15-month-old cat that developed rabies. It had been vaccinated at 5 months of age and was not yet due for a booster, which would have been required at 17 months of age

Rabies was also diagnosed in a dog and cat that had been vaccinated but were overdue for their boosters. Both initially received one dose of a 3-year vaccine, but they did not received the booster that is supposed to be given 1 year later. (Even with 3-year vaccines, pets are supposed to be given their first booster (i.e. their second dose of vaccine) after 1 year, before moving to getting boosters every 3 years). The dog was vaccinated 2 years and 9 months earlier. Twelve days after being exposed to a rabid skunk it was given a booster, but it developed rabies nonetheless and died 8 days later. The cat was vaccinated 2 years and 3 months earlier.  It apparently did not receive a booster after it was exposed to rabies, and subsequently also died of rabies.

Another six dogs and three cats that were vaccinated developed rabies, but all of these were overdue for their booster or had been vaccinated less than 30 days before rabies exposure. These were therefore not considered vaccine failures.

This information should not be taken as an indication that rabies vaccination is not useful or that current vaccination protocols are inadequate. This involves a very small number of animals, and only one that was properly vaccinated. Rather, it should be a reminder that vaccination is not infallible and that the possibility of rabies cannot be summarily dismissed just because the animal has been properly vaccinated.

(click image for source)

Swedish antimicrobial guidelines

The Swedish Veterinary Association has released an English version of their 2009 "Guidelines for the clinical use of antibiotics in the treatment of dogs and cats". It's a very comprehensive document that goes through various medical conditions and discusses antibiotic use recommendations. As concerns about antibiotic use and misuse increase, more organizations are putting the significant effort that is required into developing such guidelines, and they can be a tremendous asset. While there are still significant limitations in the available research needed to produce evidence-based guidelines, a combination of careful review of existing information and expert opinion can provide good guidance for treatment of infections in companion animals.

There are always a few disclaimers that need to be given when presenting antibiotic use guidelines:

  • They are guidelines, not standards. They provide a general overview of the issues and how to manage most patients, but some patients don't read the book and need to be treated differently.
  • Disease and drug resistance patterns vary between regions. These patterns need to be considered, particularly when considering guidelines produced in another area or country.
  • Things change over time. As guidelines age, some parts of them may become less relevant.
  • There are differences in antibiotic access and licensing between regions.

Regardless, sound guidelines like these are needed and will hopefully help improve both patient care and control of the scourge of antibiotic resistance.

Infectious disease considerations for fostering pets







Are there any "resident" pets in the household?




How do you reduce the risks associated with fostering animals?


If you have pets of your own:



(click image for source)

Whooping cough and pets

A large whooping cough (pertussis) outbreak has been ongoing in people California in 2010. This bacterial infection, caused by Bordetella pertussis, is a highly transmissible disease that can result in serious problems (including death) in young infants. At last report, there were over 6000 cases of whooping cough, making this the largest outbreak in 60 years. Over 200 infants have been hospitalized, and there have been at least 10 deaths. Nine of the 10 deaths were in infants less than two months of age.  Infants in this age group have little to no immunity to the disease because they haven't been vaccinated, and they are more prone to severe complications.

Bordetella pertussis is a human bacterium. It does not infect animals and animals are not direct sources of infection. (Actually, experimental infection of neonatal puppies with large doses of B. pertussis can result in shedding of the bacterium by a small percentage of dogs, but that's not particularly relevant to the normal household situation). Therefore, people don't need to worry about infecting their pets and pets passing the infection on to other people. However, it's not impossible that pets could play an indirect role in transmission. A pet's haircoat could possibly become contaminated with the pertussis bacterium from someone coughing around it, or touching it with contaminated hands. The bacterium could survive on the haircoat for a while (probably days), and someone could potentially get the bacterium on their hands by petting it, and subsequently become infected.

What are the odds of this happening? Who knows. It's not something that anyone has investigated, as far as I know.

Could dogs and cats be important sources of pertussis in households? Probably not. I assume that if there is a person with whooping cough in a household, that person is more likely to be the source of infection for other people than a pet. 

Could pets spread pertussis outside the home? That might be a more realistic concern. People with pertussis might keep themselves away from others and stay at home, but if they contaminate their dog's coat and the dog meets people on a walk or at the park (or at a veterinary clinic, or anywhere else), I have to wonder whether there could be the potential for spread of the disease.

What should we do about this? Common sense should prevail, and itt's important for pertussis as well as other diseases. If someone in the household has an infectious disease that is transmissible and for which a pet could potentially be a vector, some basic precautions should be taken. Good attention to hygiene might help reduce contamination of the pet's haircoat. This includes regular handwashing (especially after coughing and before petting an animal), avoiding coughing close to the pet and not letting the pet sleep close to the person's head. Keeping the pet away from people outside the house, or at least limiting it's contact with high-risk people might also be useful. In particular, keeping pets that might have been contaminated away from infants would be wise.

Overall, the risks are very low. We don't need to fear dogs and cats as potential pertussis vectors. However, in the absence of proof that there's no risk, and with a highly transmissible and potentially serious disease, use of some simple infection control measures makes sense.

Probiotic safety

The November edition of Emerging Infectious Diseases contains a commentary about probiotic safety. The paper, entitled "Regulatory Oversight and Safety of Probiotic Use" (Venugopalan et al. 2010), focuses on a probiotic yeast, Saccharomyces boulardii, which is increasingly being used for treatment or prevention of Clostridium difficile infection in people. Because it is marketed as a dietary supplement, this yeast doesn't have the same requirements for demonstration of safety and effectiveness as a "drug" would. Systemic Saccharomyces infections have been reported, predominantly in people who are critically ill or who have other risk factors for an infection caused by a microorganism that is typically harmless.

The lack of regulatory oversight limits the identification and reporting of problems associated with probiotic administration, and means that safety testing is not required, even if the product will be used by high risk individuals. Often people consider probiotics completely innocuous, and they don't think about the potential for complications. While very low, the risk of infection caused by the probiotic organism itself needs to be considered, especially when dealing with high risk patients and situations for which there is little proof that probiotics might be effective. 

Are probiotics safe for use in animals such as pets and horses? Probably.  For the vast majority of animals, the majority of probiotics are likely safe. Given the very lax nature of licensing and poor reporting of complications, it's hard to be definitive, but the likelihood of a significant problem occurring from giving an animal a probiotic is pretty limited. The fact that most commercial products actually contain few live organisms, a fraction of what is claimed on the label, probably increases safety (while also decreasing the chance that they work).

My general line is that probiotics are unlikely to do any harm for your average healthy animal. I have no problem with people trying probiotics in those cases, with the understanding that we really have little evidence that they work, but that they might. I am hesitant to use them (or recommend them) in very young animals, very old animals and animals with compromised immune systems. These types of animals are at increased risk of infection by even rather innocuous organisms that would not likely cause disease in other animals. Since the evidence that probiotics might work is lacking, I'm more careful when dealing with such high-risk groups. What we really need is sound research to provide the required evidence of probiotic safety and effectiveness.

Image: Coloured scanning electron micrograph of Saccharomyces boulardii (source:

Rabies galore

ProMed's monthly rabies update contains some recurring themes:

  • A couple of incidents of dog versus rabid raccoon. The dog usually comes out on top, but the raccoon can exact revenge at the end of the day through the need for quarantine or euthanasia. If the dog is not vaccinated, a long quarantine or euthanasia is required. If the dog is vaccinated, only a shorter observation period is needed.
  • A rabid skunk was found wandering around during the day with a wobbly gait and drooling. Any wild animal that is acting strangely should be considered rabid until proven otherwise. They don't have to be showing signs of severe neurological disease. Something as simple as not being afraid of people or wandering around in areas or at times when they would not usually be found should raise the suspicion.
  • A child who was sleeping outside woke up to "find a raccoon, kind of, scratching at his leg." (I  assume they mean it was "kind of scratching at the kid's leg," (whatever that means), instead of it was "kind of a raccoon.") The raccoon wasn't caught for testing but the child is undergoing post-exposure treatment because a normal raccoon wouldn't be expected to do that, so there is a significant chance of rabies exposure. Scratches are not high risk since rabies virus does not live in the claws, however it is possible that saliva from the raccoon could have been present on the animal's feet or the raccoon could have licked the child before scratching, such that the scratches could have then inoculated rabies virus into the tissues.
  • A couple of reports of rabies in rabid kittens. These cute little rabies vectors cause repeated problems, and lead to public alerts notifying anyone who may have handled the kittens to get evaluated to see if they need post-exposure treatment. Handling of strays should be avoided.
  • A family received post-exposure treatment after being bitten by their rabid cat. Vaccination of pets is not just for the health of the pet. It's to reduce exposure of people as well.

2009 US rabies recap

2009 animal rabies statistics have recently been published in the Journal of the American Veterinary Medical Association (Blanton et al 2010). Here are some highlights:

  • 6690 rabid animals were identified, along with four human cases. (One of those human cases was associated with travel to India, as described as described in a recent post).
  • Rabid animals were identified in 49 states and Puerto Rico.
  • 92% of infected animals were wildlife. Raccoons were the winners (actually, the losers, I guess) with 2327 cases, followed by 1625 bats, 1602 skunks, 504 foxes, 300 cats, 81 dogs and 74 cattle.

It is important to remember that these are rabies diagnoses, not all rabies cases. Certainly, more animals died of rabies and were not tested. These numbers may represent the "tip of the iceberg," particularly for some wildlife species. This can impact on the accuracy of the relative numbers between species, and year-to-year changes in cases, but doesn’t change the fact that rabies is present, widespread, relatively common and can infect a wide range of animal species, including pets. It also highlights why vaccination of pets is still important.


Peritoneal dialysis infections and pets

Pasteurella multocida is a bacterium that is commonly found in various pet species. It typically inhabits the upper respiratory tract of healthy pets, although it is an important cause of respiratory disease in rabbits ("snuffles"). It is also a zoonotic pathogen, and human infections are sporadically reported. Most are associated with bites, mainly from cats. Others have involved pets licking wounds or broken skin. Infections seem to be a particular concern in people undergoing dialysis because of kidney failure. Infections have been associated with things like cats chewing on dialysis tubing and pets having contact with catheter sites.

A recent report described another dialysis-associated infection in person with chronic kidney disease and diabetes (Satomura et al 2010, Ther Apher Dial). The person developed peritoneal dialysis-associated peritonitis. Peritonitis is infection of the internal lining of the abdominal cavity (the space between the intestines/other abdominal organs and the body wall). For peritoneal dialysis, a catheter is left in place which passes through the body wall, and infections can occur from bacteria migrating through or along the catheter and into the peritoneal cavity. In this case, Pasteurella multocida was isolated from the infected peritoneal fluid. The source of infection wasn’t clear, and no obvious risk factors like a cat gnawing on the catheter were reported. However, the same bacterium was isolated from a throat swab taken from the person’s cat. Given how common this bacterium is in cats, how uncommon it is in people, and previous reports of cat-associated infection, it’s logical to assume that the cat was the source.

The fact that no clear risk factors were identified in this case highlights the ever-present (but still relatively low) risk to people with dialysis catheters who have contact with cats. Certain things like keeping the cat away from the catheter site and other dialysis items are common sense and presumably very important. However, general hygiene measures are also probably very important. It is logical that a cat owner could frequently get this bacterium on his or her hands from regular interaction with the cat, or potential from contact with objects like food and water bowls. Good attention to hand hygiene, especially before touching the catheter or any dialysis items, must not be overlooked, and should be an important part of counseling of dialysis patients who own pets. Unfortunately, the risks associated with pets are not always discussed by physicians (who may not even ask about pet ownership), so some people don’t get the required information.

Note: Image is from It's presumably meant to be a cute image showing a happy (and otherwise healthy) kid undergoing dialysis. It's interesting that they show a cat in the picture, but no where on the page is there any mention about infection control measures that should be taken around pets. It seems like a missed education opportunity to me.


Psst...Wanna vaccinate your dog?

To me, a good general rule is "avoid buying things that are offered for sale at discount prices by a guy in a parking lot." Unfortunately, many people can't seem to pass up a "bargain" and can end up paying more in the end.

A good case in point is a man who was offering rabies vaccination of pets in retail parking lots in southern Oklahoma. James Allen advertised his vaccination "business" on Craig's List and set up shop in various parking lots. He also signed vaccine certificates and listed himself as a veterinary technician. (One problem is that veterinary technicians aren't allowed to sign rabies certificates. Another is that he is not one).  Mr. Allen has yet to be apprehended.

Mr. Allen is suspected of vaccinating hundred of pets with what is, at least from a regulatory standpoint, worthless vaccine. Since the vaccine wasn't administered by a veterinarian, all of those animals are considered unvaccinated. Therefore, if they are exposed to rabies, they face the prospect of euthanasia or a strict six-month quarantine.

Rabies vaccine must be given by a veterinarian in order for government authorities to consider an animal vaccinated in most regions. Mandating that rabies vaccine be administered by a veterinarian isn't a money-grab or veterinarians protecting their turf - it's a government regulation aimed at protecting pets and the public. Restricting rabies vaccination to veterinarians helps ensure that only proper vaccine is used, that the vaccine has been properly handled and administered, and that vaccination is adequately documented. In the absence of clear proof that an animal was properly vaccinated, it has to be considered unvaccinated, because you must err on the side of caution with a deadly disease like rabies.

It's pretty sad that it's so easy to get rabies vaccine in Oklahoma. It should only be available for purchase by veterinarians, but it's apparently easy to obtain from farm and ranch stores. Apparently, stores in Oklahoma can sell the vaccine but are supposed to post a notice saying animals are not  considered vaccinated if it's used. Why you'd allow a store to sell the vaccine when you don't recognize it as effective is beyond me, but that's what's happening.

(click image for source)

Rabies vaccination of kids in the Philippines

The Philippine Information Agency has issued a press release detailing a rabies vaccination program for 5000 public school children in the province of Camiguin. This is prophylactic (preventive) vaccination, not post-exposure treatment.

Routine rabies vaccination is recommended for people at increased risk of exposure. Classically, this involves veterinary personnel, people working with wildlife, people working with strays or feral animals, and similar groups. Routine vaccination of the general public is not used because of the high cost and low need, given the average person's low risk of exposure and the availability of effective post-exposure treatment. By providing vaccine prophylactically, authorities are implying that the rabies exposure risk is quite high for these children.

A Camiguin health office official is reported as saying that the pre-exposure series, consisting of 2 doses, will save money compared to the post-exposure regimen of 4 doses plus a shot of anti-rabies antibody. However, that doesn't make any sense. From a cost standpoint, prophylactically treating everyone with 2 shots only saves money if over half of the population would otherwise need 4 shots. I know rabies is a problem in that area, but certainly half of the kids in the area won't exposed. Further, what really blows a hole in this reasoning is the fact that a vaccinated person who is exposed to rabies should receive a booster series of 2 vaccines regardless, thus bringing the total to 4 shots. People who have been vaccinated don't get the antibody shot if they are exposed, so that does save a little money.  (On a side note, routine vaccination usually involves 3 doses, and the release says people will get two doses but will get vaccinated on days 0, 7 and 21 or 28. That's 3 doses, which makes the math even more questionable). 

If rabies is epidemic in the area, if it's not being controlled well by other means and if there is rampant exposure of children, vaccination may be a reasonable option. However, rabies is basically 100% preventable with proper post-exposure treatment. Rabies deaths are usually because people don't seek, or are not given, proper treatment in a timely fashion. Educating the public to reduce the risk of rabies exposure and to seek medical care, ensuring that there is adequate awareness about rabies among medical personnel and ensuring that adequate vaccine and antibody is available for exposed individuals seems to be a much more logical approach

I was actually wondering whether this press release was real. I did some searching and this agency is an official government agency and a member of the presidential communications group. It would be really nice to see more details about why this decision was made, particularly some of the evidence that was used to determine that this was needed.

It's important to take rabies control seriously. The main problem with rabies in many areas is a lack of effort or adequate resources directed against stray animal control, animal vaccination, public education, medical education and availability of proper treatment. Working on those would seem to me to be a better approach than an expensive and somewhat questionable mass vaccination program of children. The reasoning in the press release is that kids might not report bites, and that is a good point to consider. But, does that actually occur and can it not be controlled by better education?

What's the cost-benefit of rabies vaccination in a situation such as this? It's hard to oppose vaccination of this fatal disease, but are there other ways to provide better overall protection?

Salmonella/salmonellosis...infection/carriage...what does it all mean?

The recent Salmonella recalls and raw food debate have led to a lot of discussion about Salmonella in pets, and also some confusion about what some different terms mean.

Salmonella vs salmonellosis

  • Salmonella is the bacterium.
  • Salmonellosis is disease caused by infection with the Salmonella bacterium.

When an animal is exposed to the Salmonella bacterium from food or feces, a variety of states can develop.

  • No Salmonella, no disease: In these cases, Salmonella does not survive passage through the intestinal tract and nothing happens. The animal doesn't get sick and Salmonella is not detectable.
  • Colonization (also called "carriage"): This is when Salmonella survives passage through the stomach and grows, at least for a while, in the intestinal tract, but does not cause disease. Colonized animals may shed Salmonella, meaning they pass the Salmonella bacterium in their feces, and may therefore be a source of infection for people or other animals. Colonized animals will most often eliminate Salmonella on their own in a short period of time (days to a couple of weeks) and usually don't get sick. It is possible, however, that a colonized animal could develop salmonellosis from Salmonella living in its intestinal tract. This is most likely to occur if something allows the bacterium to overgrow in the intestinal tract or reach the bloodstream, which is most likely in young, old or sick animals.
  • Transient passage: This occurs when live Salmonella that have been ingested survive passage all the way through the intestinal tract, but without the bacterium becoming established in the body and without disease. Salmonella can be detected in feces. It's hard to distinguish transient passage from short-term colonization, and it's not clear whether transient passage really occurs.
  • Enteric salmonellosis: This is the most common form of disease, characterized by diarrhea and potentially varying degrees of depression, weakness, lethargy, decreased appetite and vomiting.
  • Systemic salmonellosis: This uncommon and severe form of disease occurs when Salmonella enters the bloodstream (by invading through the intestinal wall) and causes a bloodstream infection and/or infection of other body sites/organs. This form is often fatal. It is most common in young and old animals, or animals with other diseases that affect their ability to fight infections.
  • Contamination: It is also possible for animals to spread Salmonella that has only contaminated the outside of their bodies. For example, a dog eating contaminated food might get Salmonella on its face. The bacterium doesn't make in to the intestinal tract and can't cause colonization or disease in the dog, but the dog's face could be a source of infection for other individuals for a short period of time, until the bacteria die or are physically removed.

Image: Salmonella sp. on an XLD agar culture plate 24 hours after innoculation. (Source: CDC Public Health Image Library #6619)

Pets in the workplace...good or bad?

Pets at work are an often contentious issue. Some people would love to take their pets to work with them to avoid leaving them home alone all day, to save money on doggie daycare, to be able to socialize with their pet during the day, and because they think "everyone will love seeing my dog."

Having pets in a workplace could be a great way to improve employee morale and for some people could be a recruitment tool. It might boost productivity if people are happier and not rushing home because they think their dog's bladder is about to burst (or, more likely, their floor is about to get peed on).

However, it could also be a great way to create strife and legal concerns. Personally, I have no problems walking into a store and seeing a dog or cat wandering around. That being said, I have above-average exposure to animals and am not deathly afraid or allergic. I'm also (currently... hopefully) not highly immunocompromised and at increased risk of an infection from a pet.

No two workplaces are exactly the same. Some businesses might be able to do it right. Some might not. Some might be willing to put the effort into it as a way to boost morale and attract good employees, some might think it's a hassle worth avoiding. If a company allows pets or is thinking of allowing pets in the workplace, they need to consider some important points:

  • Are any people that MIGHT come into contact with the animals fearful or allergic? This is difficult to determine unless you have a small workplace and good communications. People that are allergic or fearful might not voluntarily offer that information because of various reasons, so just saying "if no one raises a concern, everyone's happy" doesn't always work.
  • Will there be any potential contact with the general public? If so, that complicates matters greatly.
  • Are there ways to properly contain and control the pets? Will the pets be allowed to roam free, be kept in the owners office, or be kept in a dedicated kennel area, away from anyone who doesn't want to see them? The more they can be contained, the better. Ideally, there would be a kennel area away from anyone who doesn't want to be in contact with the animals, but close enough that it is easy for owners to check on their pets and take proper care of them.
  • Will having pets there be a disruption to the owner or other employees? A happy workforce is more productive. That's the ideal situation. A workforce distracted by a playful puppy or a cat who loves to flop across your keyboard may not be as efficient.
  • Is there an area where a dog can be safely walked to urinate and defecate?
  • Are there any reasons that having a pet there causes an unacceptable public health concern (e.g. restaurants).
  • Is the business willing to accept the liability issues that come with having animals there? If a pet bites or scratches someone, the business' name will be first and foremost on the lawsuit, I assume.
  • Will the business create a written protocol to address animals in the workplace? This would cover things like where to keep the animal, how to handle it, preventive medicine requirements (e.g. rabies vaccination), when the animal can't come to work (e.g. when it's sick) and other relevant factors.
  • Is there a way to modify the policy over time if something happens? For example, if a new employee is hired and is severely allergic, will the rules be changed? If so, are people notified up front that while they may be able to bring their pets to work now, that can change at any time?

If the workplace can't consider and address all of these areas, then pets are clearly not appropriate. If they can, then there may not be a problem. The key is thinking about these issues in advance, not after:

  • the pet has bitten some who is now upset, threatening to sue and demanding proof of rabies vaccination
  • a person that gets fired claims their poor job performance was because they were afraid of the dog and also afraid of speaking up about it
  • the dog causes a disease outbreak
  • the public health department comes in to investigate an inappropriate situation

Photo credit: James Cheng (source:

Rabies vaccination requirements

I periodically get questions about whether rabies vaccination is really required or if it's just a good idea. There's not a straight answer because legal requirements vary by region. In Ontario, Regulation 567 of the Protection and Promotion Act states that all dogs and cats three months of age or older that reside in specified areas of the province must be vaccinated. Further, animals must be revaccinated by the date specified on the certificate of immunization. Basically, this means that all dogs and cats must be vaccinated and they must be up-to-date on the vaccination, based on the type of vaccine that was used.

Even if vaccination isn't legally required, if rabies is in an area, it's a good idea because:

  • If a pet gets rabies, it will die.
  • If a pet gets rabies, owners or other people in contact with it may need post-exposure treatment.
  • If a pet gets rabies, it could infect people with this almost invariably fatal disease.
  • If an unvaccinated pet gets exposed to rabies, it will need a strict 6-month quarantine or euthanasia. (Euthanasia is common in these situations.) If the pet was vaccinated, all it needs is a 45 day home observation.

Rabies vaccination of pets is easy, cheap and safe, and often required by law.

Image source:

What not to do in a vet's office has an interesting article about "10 things not to do with pets in a vet's waiting room." They're all good points, and I've put an infectious disease/infection control spin on them below:

1. Don’t fail to contain your cats. Even if your cat is the sweetest thing on record, some other animals may not agree. The last thing we want is to see in our lobbies is an altercation in which one animal dies. Cat carriers are cheap and widely available. Use them.

2. Don’t give dogs free reign.  Don’t use retractable leashes!

  • You wouldn't (hopefully) go into an emergency room and lick the face of the person puking in the corner or the kid hacking up a lung. Your pet's not as discriminating. Some pets are at the vet because they are sick. You don't want your pet to get what some other pet has. Also, not all dogs and cats are social, especially in a strange environment. You don't want to change your vaccination appointment to a "vaccinate and stitch up the big wound on my dog's face" appointment.

3. Don’t bring in animals you cannot personally control.

  • As above. Lack of control equals increased risk to other animals, your animal, and potentially other people.

4. Don’t do the puppy park meet-and-greet thing. The vet’s is not the dog park. It’s a strange environment in which pets don’t always act the way you expect them to. Moreover, in a veterinary hospital the onus is on the doctor’s staff to keep your dogs safe. Please keep all pets apart. After all, no matter how well you know your pet, can you honestly say you know someone else’s?

  • Same as above. More mixing and more contact equals a greater risk of disease transmission. That's acceptable in many situations where the risk of coming into contact with an infectious animal is low, but the odds are higher in a place where sick animals congregate.

6. Give the cell phone rest. In a place as potentially anxiety provoking as the vet hospital, cell phones can be a hazard. Even if you don’t feel the anxiety, your pet certainly does. She deserves the comfort of your undivided attention for her safety and her stress level.

  • Not really an infectious disease issue but it's annoying.

7. Don’t walk a dog into a packed waiting room. If the lobby is crammed wall to wall with pets, don’t chance it. Ask someone to let the receptionist know you’re waiting outside. Or use your cell phone for something really useful for once.

  • Good point. I'd take that a step further. Don't take a potentially infectious pet into a waiting room, packed or not. If you have an animal that might have an infectious disease (e.g. diarrhea, sudden onset of coughing and/or sneezing) it would be ideal to call when you arrive so they can take your pet right back to an exam room or isolation for examination. That way, if your pet is infectious, you won't expose other animals. We're trying to get more clinics to be proactive about doing this, and hopefully your clinic would mention it, but if they don't, feel free to bring it up yourself.

8. Don’t fail to tell the receptionist ahead of time if your pet is severely anxious or aggressive. All hospitals appreciate the warning when you make your appointment. It gives us a chance to offer you back-door alternatives or other concessions to your pet’s unique behavior issues.

  • Good point. "If your pet is severely anxious, aggressive or might have an infectious disease" would be better.

9. Don’t bring small children unless you can’t help it. A busy animal hospital is tough on small kids. They’re not old enough to benefit enough from the educational experience relative to their risk of getting hurt.

  • Sometimes you have to, but if you can avoid it, that's preferred. Vet clinics can be busy. There are a lot of animals around and it may be hard for a child to resist reaching out for another animal. I haven't seen any data on bites and scratches in waiting rooms, but they certainly occur. As well, if you are distracted by your child, you may not be able to tell your vet all the relevant information or ask all the questions you have.

10. Don’t be rude. Courtesy is king. Kill them with kindness. I shouldn’t have to offer so many versions of the same cliche, but the fact that they all exist is fine testament to their utility.

  • Again, not necessarily an infectious disease concern, but really being polite and considerate to those around you applies to just about any situation, and generally makes everyone feel better and makes things go smoother.


NDM-1, a new threat?

"NDM-1 superbugs" have received a lot of press the last day or two. That's lead to questions about whether there may be any risks for pets.

It's good to see that people are thinking about how this might affect other animal species. That's a thought process that would have been rare a few years ago, and which was probably fostered by the emergence of MRSA in animals.

What it NDM-1?

  • NDM-1 stands for New Delhi metallo-beta-lactamase 1. It is a type of beta-lactamase, an enzyme that inactivates certain antibiotics (those of the beta-lactam class). The concern with NDM-1 is that it inactivates carbapenem antibiotics, an important class of drugs that is often used to treat serious and life-threatening infections.

Where is it a problem?

  • It's currently mainly a problem in India and Pakistan.

Will is spread to other regions?

  • Probably. It's easy for people to travel around the world quickly, and it's easy for new microorganisms to travel with them. A bug that originates in one region can very easily spread across the planet. NDM-1 has been found in a few other countries, including Australia, parts of Europe and Canada. There is concern that the increase in health tourism (traveling to countries like India for cheap and quick procedures like elective surgeries) will result in spread of NDM-1, since people could pick up the bug in hospitals and bring them home. Transmission of NDM-1 in hospitals from patients that had healthcare procedures abroad has been documented in the UK. People traveling to regions where the organism is present for other reasons are also possible sources.

Can it affect pets?

  • Probably. Two important types of bacteria, E. coli and Klebsiella spp, can carry NDM-1 (and probably other related bacteria can as well). These can cause infections in many different species. As more people carry bacteria with NDM-1, there's a greater chance that pets will be exposed, as we've clearly seen with MRSA. Dogs that visit human hospitals and pets owned by people who visit India for healthcare are probably at greatest risk, with pets of people who have been hospitalized and pets of healthcare workers likely also at increased risk.

What can we do to reduce the risks?

  • Nothing specific. The most important factor here is control of NDM-1 in human hospitals. At the animal level, there's nothing in particular we can do about NDM-1 at the moment. The keys are prudent use of antibiotics (to reduce the likelihood that resistant strains will get established in pets), good general infection control in households and veterinary hospitals (to reduce opportunistic infections by bacteria that can carry NDM-1), and making sure that cultures are taken when infections are present (to find out if/when this becomes a problem).

Plague in Montana cat

A cat from Ennis, Montana, has been identified as the area's first case of plague in a pet cat this summer. Plague is a disease that conjures up images of medieval pandemics and calls of "bring out your dead" (along with calls of "I'm not dead yet" from Monty Python fans).This bacterial disease, caused by Yersinia pestis, is not just of historical interest, however. It is still an important disease in some regions. In the US, it is present in wildlife in parts of the southwestern US and circulates in wild rodents. Domestic pets mainly become infected through eating infected rodents, but the bacterium can also be spread by fleas.

Cats are quite susceptible to plague, and can develop classical bubonic plague, septicemic plague or pneumonic plague, and only about 33% of infected cats survive. Dogs are relatively resistant to the disease.

Transmission of plague from pets to people is uncommon but most often involves cats. Veterinary personnel and pet owners that care for sick cats are at highest risk. While transmission from cats to people is rare, about 20% of people infected from cats die, so it certainly warrants some precautions.

In areas where plague is present, cat owners should consider the following:

  • Keep cats indoors to prevent them from hunting and eating rodents.
  • Keep rodents and other wildlife out of the house.
  • Have a flea control program in place to prevent or treat flea infestations in pets.
  • Never catch and keep wildlife (e.g. prairie dogs) as pets.
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Salmonella recalls: When to test

The recent run of Salmonella recalls in dry foods, raw foods and supplements has resulted in a lot of questions about when animals should be tested for Salmonella. In general, testing is only indicated in animals that have disease suggestive of salmonellosis. Diarrhea is the main issue, but other problems such as fever, decreased appetite and bloodstream infections can also occur. Clearly, any animal with signs such as these needs to be tested for Salmonella. However, there is no indication to test healthy dogs and cats that have been exposed to recalled products.

Why is that? An important concept in medicine is that you should always have a plan about what to do with the results of diagnostic tests - the result should have an impact on what you do. When you think about what would happen with a negative versus a positive test for Salmonella in a healthy pet, it shows why testing is not useful.

What would I tell you about a negative result?

  • I'd say it means the animal is probably negative, but it could be a false negative because of intermittent shedding of Salmonella in stool or a false negative test result.
  • I'd also say that even if there was no Salmonella, every animal is shedding multiple potentially harmful pathogens in its stool.
  • So, I'd emphasize that if the animal became sick, Salmonella still needs to be considered and that good hygiene measures should be used around the animal (particularly its stool).

What would I say about a positive result?

  • I'd say that means the animal was shedding Salmonella at the time the sample was collected, but that doesn't tell us if the animal is still shedding or how long it will do so.
  • There's no indication to treat the animal. There is no evidence that treatment of dogs and cats that are shedding Salmonella is needed. There's also no evidence that it's effective. In fact, there are concerns that giving antibiotics could prolong shedding of Salmonella and that it could increase antibiotic resistance.
  • Salmonella is certainly a public health concern, but there's not much specific to be done.
  • So, I'd emphasize that if the animal became sick, that Salmonella still needs to be considered and that good hygiene measures should be used around the animal (particularly its stool).

Since my recommendations for a positive result and a negative result from a healthy animal would be the same, why test?

Cats and bats and rabies

I had an advice call the other day about two cats that were found with a dead bat. One cat was vaccinated against something (not sure what or when) while the other cat was unvaccinated. This is a situation that, if managed properly, can be very minor, but if handled improperly, can be a major problem, even resulting in death of the animals.

Bats are notorious rabies vectors. The odds of this bat carrying rabies are probably low, but they are not zero and a rabid bat is going to be more easily caught than a healthy bat. Any contact of an animal with wildlife in areas where rabies is present is considered a possible rabies exposure unless proven otherwise. The only way to do this is to have the bat tested.

If the bat is tested and is negative, then everything's fine. If it's positive, then the vaccinated cat would need a rabies booster vaccine and would have to be observed at home for 45 days. The unvaccinated cat would need a strict six month quarantine or would have to be euthanized. So, it's clear that the rabies status of the bat and the vaccination status of the cats are crucial.

Here's what to do in a case like this:

  • Get the bat. The bat needs to be tested so you have to maintain control of it. Don't let the cat eat it or run off with it. Don't leave it outside where a person or animal could walk off with it. Put it in a bag or container, without having direct contact with it (e.g. use gloves or a scoop to pick it up). Be very careful if it's not completely obvious that the bat is dead, because an injured bat might look dead but still be able to bite.
  • Submit the bat for testing. In Canada, that's done through the Canadian Food Inspection Agency. Make sure they know that an animal has been exposed to the bat. They would not likely test the bat if there was no exposure. They can be contacted directly or through your veterinarian. There is no charge for testing.
  • Find out the vaccination status of the cat(s). You need to know when the last rabies vaccine was given and what type of vaccine was used (1 year or 3 year). You need to be able to demonstrate that the pet is current on its rabies vaccination if the bat is positive and you want to avoid the long quarantine.
  • Figure out why/how/where the cat(s) caught the bat, and whether that can be avoided in the future.

(click image for source)

Diagnosing Salmonella

Recent Salmonella recalls have led to some questions about the best way to diagnose salmonellosis in dogs and cats.

The first issue is when to test. In general, there is no indication to test healthy animals. Testing should be reserved for animals with diarrhea or other signs of salmonellosis (e.g. fever).

When testing is indicated, a few things should be considered:

The Sample

  • A fresh sample is best. It should be submitted for testing as soon as possible, but it can be kept cool (i.e. refrigeration temperature) for a day or more if it can't be submitted right away.  (Do NOT keep a fecal sample in your fridge at home! Take it to your local vet clinic and they will keep it in a designated specimen fridge.)
  • More is better. A reasonable volume of stool (e.g. a tablespoon or two) is preferred to something like a rectal swab. Testing can be performed on rectal swabs but they are lower yield because they contain a lot less stool.  See image right: standard-size 30 mL fecal sample containers (click for source).

The Test

There are two tests used to detect Salmonella in feces: culture and PCR.

Culture is used to grow and isolate the Salmonella bacterium. Usually, enrichment culture is used, whereby the sample is first cultured in a selective broth culture medium, then put on culture plates. This increases the recovery rate but takes more time.

Advantages of culture are:

  • A positive is definitive - the bacterium is definitely there and alive.
  • An isolate is available for subsequent testing such as determining the susceptibility to antibiotics and typing it to see what strain is involved.

Disadvantages of culture:

  • Salmonella can be hard to grow for labs that don't have a lot of experience and good protocols.
  • A few days are required to obtain results, particularly if proper enrichment methods are used.

PCR (polymerase chain reaction) is a molecular diagnostic test that looks for DNA from a particular organism (in this case, Salmonella).

Advantages of PCR:

  • Speed. Results may be available within 24 hours.

Disadvantages of PCR:

  • Tests validated for dogs and cats are not usually available.
  • The test detects both live and dead bacteria, so a positive result could theoretically be from ingestion of dead (and therefore irrelevant) bacteria.
  • False negative results can occur from low levels of Salmonella or substances in the stool sample that inhibit the test.
  • Lab quality control is critical but not always good.

Current recommendations are to base diagnosis on culture. PCR can be used as a faster presumptive test, but culture should be performed to confirm the diagnosis and get a bacterial isolate that can be further tested for antibiotic sensitivity and typed to see what strain is involved.

Peritoneal dialysis and pets

Peritoneal dialysis is used to treat some people with chronic kidney failure. Infection is a major concern, particularly peritonitis (infection of the lining of the abdomen) because peritoneal dialysis involves having an indwelling catheter that goes through the skin and body wall directly into the abdominal cavity.

Infections can occur from bacteria that inadvertently get flushed into the abdomen during dialysis treatment or potentially migrate along the side of the catheter. Accordingly, most infections associated with peritoneal dialysis are caused by bacteria that are found on peoples' skin, such as Staphylococcus aureus.

While the vast majority of peritoneal dialysis infections are human-associated, infections from pets have been reported. Multiple different pet species have been implicated, even hamsters - one case report described an infection in a child that was thought to be caused by a hamster that slept in the same bed as the child (Campos et al 2000).

A recent study in the journal Seminars in Dialysis (Broughton et al 2010) involved a review of the scientific literature for reports of pet-associated peritoneal dialysis infections, as well as a review of records from the authors' peritoneal dialysis unit.

In their review, they identified 124 reported infections caused by zoonotic microorganisms in the literature, involving 12 different microorganisms. The most common microorganisms were Campylobacter, Pasteurella, Zygomycetes, Neisseria, Rhodococcus, Listeria, Mycobacterium avium complex, Capnocytophaga spp, Salmonella, Brucella and Bordetella bronchiseptica. However, only a subset of these were probably associated with pet contact, and retrospectively determining the sources is quite difficult for some. For example, Campylobacter and Salmonella could as easily (or more easily) come from contact with raw meat as from pets. Infections were fatal in 13.5% of cases, demonstrating why this is an important issue.

The most common bacterium causing convincing pet-associated infections was Pasteurella, which can be found in the mouths (and other places) of healthy pets. It is a common cause of pet bite infections and it makes sense that Pasteurella could contaminate pet owners' hands or the dialysis catheter site. In the study of their own hospital's cases, the authors found similar findings, with a low rate of zoonotic infections and a predominance of Pasteurella among those.

Literature reviews aren't a great way of determining the true scope of a problem, because they require people to:

  1. identify the infection
  2. identify a pet as a possible source (often the weak link; furthermore, identifying an infection caused by a potentially zoonotic microorganism doesn't necessarily mean a pet was the source)
  3. decide to write a case report
  4. get that case report accepted by a journal

Studying medical records has limitations as well, since steps 1 and 2 still need to be performed (with the weak link again being thinking about a pet-association). So, care should be taken when interpreting the results of this study. However, while the results indicate that pet-associated peritoneal dialysis infections do occur, they are probably relatively uncommon.

While pet-associated infections are likely uncommon, any peritoneal infection can be a major problem, so common sense measures that would likely reduce the risk should be used:

  • Avoid contact of pets with the dialysis catheter and catheter site
  • Wash hands after having any contact with pets
  • Don't let pets sleep in the bed
  • Wash hands before touching the catheter


  • Physicians should be aware of the potential for pet-associated infections, and pet contact by their patients
  • If a pet (usually a cat) bites the tubing, this should be reported to a physician ASAP and preventative treatment for infection might be indicated
  • Initial antibiotic therapy choices should cover common pet-associated pathogens if there is a history of contact of pets with the catheter or tubing.

People with peritoneal dialysis catheters shouldn't fear their pets, and there is no need for these people to get rid of pets (although they should avoid high-risk pets like reptiles). Pet owners are presumably at somewhat higher risk than non-pet-owners, but the risk appears to be fairly low. In most situations, the positive aspects of pet ownership probably outweigh the risks.

Image: Schematic diagram of peritoneal dialysis (click image for source)

Expanded Iams recall

Following on the heels of a limited recall of feline dry renal diets because of potential contamination with Salmonella, Proctor and Gamble has now recalled all Iams Veterinary Dry Products, as well as Eukanuba Naturally Wild, Eukanuba Pure and Eukanuba Custom Care Sensitive Skin. These products are sold across the US and Canada, and all products with best-before dates between July 1, 2010 and Dec 1, 2010 (so, presumably everything that is on the market at the moment) are included. The broad scope of the recall is apparently a proactive measure based on the premise that since Salmonella was found in some products made at a particular production facility, there is the potential for contamination of everything made there. More data about what they have found and how widespread the contamination is would be nice (but is not forthcoming at the moment).

No illnesses have been reported. If your pet is being fed one of the recalled diets and develops diarrhea, vomiting or other signs of illness (e.g. weakness, fever, decreased appetite), it is important to consider the possibility of Salmonella. Similarly, if any people in the house develop these types of symptoms, they should make sure their physician knows they may have been exposed to Salmonella. Presumably, the level of contamination was low and the risks to the general public (human and canine/feline) are relatively low, with higher risks to people and animals with compromised immune systems or other diseases that limit their ability to fight off a bug like Salmonella.

Is Staphylococcus schleiferi zoonotic?

Methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) get a lot of media attention because of the ever increasing numbers of infections in dogs and cats, and concerns about transmission to people. However, there are many other methicllin-resistant staph of varying relevances. One is an interesting related bug called Staphylococcus schleiferi.

There are actually two types of S. schleiferi:

  • S. schleiferi schleiferi: This is a coagulase-negative subspecies that occasionally causes skin and ear infections in dogs (and uncommonly cats). It can also be found in healthy animals. There are a few reports of infections in people, mainly surgical site and wound infections in individuals who are at high risk of infection because of hospitalization, surgery or other factors.
  • S. schleiferi coagulans: This is a coagulase-positive subspecies that may be more common in dogs and cats than S. schleiferi schleiferi, causing skin and ear infections and also being found in healthy animals. Human infections are very rare.

Currently, there is little to no evidence the animals are a source of human infection with S. schleferi and human infections appear to be very uncommon. However, this is an area that hasn't been studied much so it's hard to say with any confidence that there is no risk. My assumption is that the risk is very low, but not zero, so while we shouldn't be paranoid, it makes sense to use some very basic infection control practices when dealing with infected animals to reduce any possible risk. These would include:

  • avoiding contact with infected sites
  • if contact with infected sites is necessary (e.g. cleaning or treating infected ears), gloves should be worn and hands washed after glove removal
  • hands should be washed thoroughly after any contact with the infected site, and regularly after contact with the animal

Quarantine of infected animals in households isn't necessary, because of the limited evidence of transmission and because healthy dogs and cats can also carry this bacterium. In veterinary clinics, isolation of infected animals is reasonable because other animals in the clinic may be at higher risk of developing infections should they become exposed.

Iams recall: Salmonella

Proctor and Gamble has announced a recall of two lots of Iams' Veterinary Formulas Feline Renal, a prescription dry cat food. The lot numbers are 01384174B4 and 01384174B2. Anyone that has this food should stop using it immediately. Since these are prescription diets that should only be available through a veterinarian, affected customers should presumably contact their veterinarian for information about a replacement or refund. If a cat that has eaten this food develops diarrhea, Salmonella should be considered as a possible cause and a stool sample should be tested.

As with most of these recalls, no illnesses have been reported, although lack of reported cases doesn't necessarily mean lack of cases. While Salmonella contamination of dry pet food diets is quite uncommon, it can happen.  It's a good reason for people to make sure they wash their hands after having contact with any pet food or the pet's food bowl, and to make sure that pet food is kept separate from food meant for human consumption.

Pet therapy: What about the risks to the animals?

There's an interesting article in today's Pittsburgh Post-Gazette about Scooter, a paralyzed cat in a custom-made cart, that visits patients at HealthSouth Harmarville Rehabilitation Hospital. It's a nice story and it's easy to see the potential appeal of a paralyzed animal whipping around a rehab hospital as an inspiration to patients.

Obviously, people like having this cat in the hospital, and he's helped some patients. That's not surprising because we know that pet therapy can be beneficial to many. My concern in this case is for the cat's health, and the heart of the issue is whether the benefits to patients are because Scooter's a paralyzed cat or because he's a cat, and whether the benefit to patients justifies the risk to the cat.

Paralyzed animals are at increased risk for certain infections. In particular, they are at very high risk for urinary tract infections. These animals tend to get recurrent urinary tract infections and enter a downward spiral of infection / treatment / infection / treatment / resistant infection / treatment / more resistant infection... and in some cases end up with infections that are very difficult or impossible to eliminate. In some cases, urinary tract infections in paralyzed individuals can result in infection spreading to the rest of the body, which can be fatal.

Back to my concerns for Scooter: We know that the hospital environment is contaminated with various drug-resistant bacteria. We know that patients in hospitals are often carrying drug-resistant bacteria. We know that dogs that participate in visitation programs are at increased risk of acquiring drug-resistant bacteria. So, do we really want to be exposing a high-risk animal to such an environment, and potentially speed up the cycle of infection that could ultimately cause severe illness or even death in the animal?

There's no clear answer, but we need to consider the risks to visitation animals, and whether the novelty of having a paralyzed cat (instead of a normal, healthy cat) visiting patients is really a significant enough benefit to justify the potential risk to the cat.

Image: A paralyzed cat using a mobility cart (source:

Internet advice: The good, the bad and the ugly

The internet can be a strange place at times. You can find great, reputable and unbiased information right next to complete garbage. Often, the garbage is pretty apparent, but sometimes it's dressed up well or mixed in with some good information. That's a problem with veterinary advice and information sites.

Among the creative myths identified in a couple of minutes of searching:

- Metronidazole is a proven treatment for parvovirus: No. Metronidazole is an antibiotic that doesn't have any effect on viruses. Antibiotics are sometimes used in the treatment of parvovirus, but they are drugs that are used to prevent or treat problems caused by bacteria from the gut entering the bloodstream as a result of the intestinal tract disease. Metronidazole won't do that.

- MRSA is a virus: You can't make much more of a basic mistake than confusing a virus and a bacterium. Anyone who says this when purportedly writing medical advice is completely clueless.

- If your dog gets an MRSA infection, your veterinarian will likely prescribe vancomycin: Only in extreme circumstances (if ever) should this ever happen. For more information on vancomycin and its use in treating animal and human infections, see our archives. (This gem is on a page that says it's information from infectious disease specialists).

-MRSA in dogs can easily become resistant to vancomycin so linezolid may be required: Fortunately, vancomycin resistance is extremely rare, having been found only a few times in people, in specific circumstances. It's never been found in a dog. Hopefully it will stay that way. (This site didn't even spell vancomycin correctly.)

- Cats can easily get a urinary tract infection if their litterboxes are not cleaned: No. There is no evidence of this and no reason to think it's an issue. Poor litterbox maintenance can lead to urinating outside of the litterbox or other problems like idiopathic cystitis, but not infection.

- In order to have a very healthy dog, it is often required to supplement your pet's diet to provide a high amount of probiotics: Nope. Certain probiotics might be useful in certain animals in certain situations, but we have no proof of this in dogs and cats, and they are certainly not needed for all animals.

There's no way to guarantee that a website is reputable or that the writers are knowledgeable, but here are some things I consider when scrutinizing information on the internet:

  • Who set up the website? Is it clear who's in charge?
  • Who wrote the information? Is it someone with actual credentials? For veterinary medical advice, is it a veterinarian? If it's a veterinarian, is it a specialist? If it's not a veterinarian, what expertise does the person have? Some people without veterinary degrees have expertise in some fields, but try to determine whether they truly have the qualifications to give advice on a particular topic. That's harder to do these days given the proliferation of mail-order "PhD" degrees, something that's not uncommonly encountered in unqualified people making poor veterinary recommendations. 
  • Why is the website there? Is it an educational site or is it there to make money? Commercial sites aren't necessarily bad but you have to consider any conflicts of interest or ulterior motives. If there is an article about something, and the last sentence tries to sell you a product to fix that problem, be careful.
  • Does the information make sense and is it consistent with other websites? You can probably find a site somewhere to support any notion that you have, but does it really make sense?
  • Is the site relevant to your geographical area? This is particularly important for infectious diseases since they can vary greatly between regions. A disease may be a big problem in one area, and a website might provide excellent advice... but only for that area. It may be completely irrelevant or inappropriate for other regions.
  • Can they spell? The odd typo probably isn't a major issue (I do it myself). However, rampant and blatant abuse of the English language and an inability to spell important words properly should be red flag.

Searching the internet for pet health information is certainly not a bad thing to do. But, you have to critically assess what you read and remember that it's not always right. Use the internet as a resource but make sure that it's to supplement advice from your veterinarian, not to replace it.

Trap/neuter/release controversy

Trap/neuter/release (TNR) programs involve trapping feral (stray) cats, then spaying or neutering and vaccinating them. Some cats are adopted, while the majority are released. The goal is to reduce the feral cat population by limiting the number of breeding animals, and to increase overall vaccine coverage in order to reduce illness and deaths. One such TNR program has come under fire in a Texas town.

In Leander, Texas, trapping wild animals (including feral cats) is illegal, but authorities have ignored the rules for groups that run TNR programs. One citizen, Carmen Amaya, is leading a charge to get authorities to start enforcing this so that TNR programs can't happen. The main reason appears to be that she's upset her dog was scratched by a feral cat and ended up with $800 in vet bills (not something I'd be happy with either, but is this really the best way to direct her anger?).

A non-profit group, Shadow Cats, has led the TNR effort and has trapped, neutered and vaccinated  about 3000 cats in Central Texas since 2004. About 500 were adopted and the rest released. The organization knows they are working outside the law and have lobbied for it to be changed. That was being considered in June, but opposition from Amaya and others has led to the creation of a task force to make a recommendation, which is due next month. In the meantime, Shadow Cats has ceased activities in Leander.

I'm not sure what the opponents to TNR really want. If it's just cessation of the program, there's no benefit to them.  Without the program:

  • Stray cats will continue to be around, and there will probably be more of them.
  • Potentially adoptable cats won't be taken into homes to improve the lives of those cats.
  • Vaccine coverage of the population will decrease. That's a critical point, because it will result in lower "herd immunity."   With herd immunity, the greater the percentage of a population that is immune to a disease (i.e. vaccinated), the lower the likelihood of the disease establishing itself in and spreading through the population, even among those individuals who don't get vaccinated.

On the other hand, if these people simply want Shadow Cats to stop releasing the neutered cats back into the neighbourhood, it means either 1) finding a way to care for all those cats in shelter, which simply isn't realistic for a multitude of reasons, not the least of which is cost, 2) releasing the cats elsewhere, which doesn't actually solve the problem, it just makes it someone else's, or 3) euthanizing all the cats instead of neutering and releasing them.  If they're hoping that by objecting to the TNR program that all the cats being trapped will be euthanized instead, they need to realize:

  • It's not going to happen as long as volunteer "rescue" groups are in charge of the program. These groups aren't going to trap and kill.
  • The city is unlikely to do it either, and there's a cost to having city personnel catch the cats and take them somewhere to be euthanized.
  • Most importantly, culling has been shown time and time again to be an ineffective way to control feral animal populations. What's needed is a combined approach that includes measures such as neutering and vaccination, education to reduce the risk of human and domestic animal exposure to feral animals, and taking steps to discourage feral animals from spending time in close proximity to people and domestic animals.

Amaya states that "her" feral cat is a nuisance and she doesn't want it on her property. So what is she trying to accomplish? If anything, her actions will just help her single stray cat turn into a large extended family of stray cats that are susceptible to rabies.

There are certainly concerns with feral cats and TNR programs. They are not perfect and not always run well. Some people are opposed to them for various reasons, some of which are quite reasonable. It's a tough issue because one person's idea of success might be completely different from someone else's. Some people focus on the number of animals, while others focus on the quality of life of the animals, public health aspects, impacts of feral cats on wild bird populations and other diverse areas. A local council isn't going to be able to solve these problems, and it really comes down to an assessment of the potential usefulness of the program and the ability of the people involved to do it safely, ethically and legally.

Personally, I'd rather see well-designed, well-run and regularly-evaluated programs to try to reduce feral cat (and dog) populations, and (perhaps more importantly) increased vaccination coverage in the feral animal population, than nothing. Feral animals aren't going to disappear if we ignore them.

Image source:

Famous Fox bitten by rabid cat

Former British pop star and I’m a Celebrity-Get Me Out of Here reality TV character Samantha Fox was bitten by a rabid cat while vacationing in Thailand. Fox was feeding stray cats near a restaurant and was attacked.

Having contact with stray animals is a high risk activity, particularly in regions where rabies is very common. When traveling, it’s important to understand the infectious disease risks in the areas you visit, and rabies is one of them. A bite by a stray animal is usually going to be considered a potential rabies exposure, unless you’re in a rabies-free country or the animal is available for observation or testing. That’s not usually the case, and post-exposure treatment, consisting of a shot of anti-rabies antibody and a series of 4 rabies vaccinations, is usually required.

Fox wasn’t particularly impressed by the treatment: "The treatment for rabies makes you feel sick and horrible, though, really fluey and shaky." Usually, the post-exposure treatment isn't too bad (I can speak from experience here) and current rabies vaccines tend to have a much lower rate of side effects than older vaccines. Fear of adverse effects shouldn’t be a deterrent to proper treatment of this almost invariably fatal disease.

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Salmonella recalls

A couple of more Salmonella recalls have occurred recently. Feline's Pride Natural Chicken Formula, a raw chicken diet, has been recalled, as has Natural Balance Sweet Potato and Chicken, a kibble diet.

Finding Salmonella in commercial raw diets is expected and I'm surprised about the recalls that have happened. If you buy raw meat, you need to assume that it's contaminated with Salmonella and various other potential pathogens. Salmonella in kibble diets is more surprising, and is a concern because people do not tend to handle kibble as potentially contaminated.

These recalls highlight a few points to me:

  • Always assume you have Salmonella and other nasties in raw meat. Careful attention to handling of raw meat and personal hygiene (e.g. handwashing) is critical.
  • While lower risk, kibble is not innocuous, so wash your hands and prevent cross-contamination of kibble with human foods.
  • "Natural," along with "organic," "super premium" and other marketing catch-words tell you nothing about the quality and safety of a product. There's no evidence that any products marketed as organic, natural, or anything else along that line are at all superior to diets produced by reputable companies, particularly diets that have undergone proper development and testing, including AAFCO feeding trials.

Rabies, rabies, and more rabies

It's not like we needed any evidence that rabies is still an active, deadly disease, but a recent ProMed-mail posting contains 16 different rabies notices. They include:

  • An animal control worker who was bitten by a rabid, stray cat that was trapped by a person in Texas.
  • Rabies exposure in an unvaccinated dog in Maryland, that resulted in euthanasia of the dog  because the owners didn't want to undertake the required 6 month quarantine for exposed, unvaccinated dogs. The dog was exposed to rabies virus while killing a raccoon.
  • Diagnosis of rabies in two trapped raccoons in New Jersey.
  • Rabies exposure in an Arizona woman who was attacked by a rabid fox while in her yard.
  • More marauding (presumably rabid) foxes attacking people and dogs in Maine and South Carolina.
  • Rabid bats and skunks in Colorado.
  • A rabid fox in Alabama.
  • Rabid raccoons in Virginia.
  • A rabid raccoon attacking a vaccinated dog.
  • Rabies exposure in people bitten or scratched by rabid stray kittens in New Jersey, Nebraska and Georgia.

Common themes or take home messages:

  • Rabies is here (in most areas, at least) and it's unfortunately not going away any time soon. We can reduce the number of affected animals and decrease the risk of exposure of people and domestic animals, however, with good prevention strategies.
  • Vaccination of pets is a cheap and effective way of protecting them, and anyone they are in contact with.
  • Keep pets away from wildlife.
  • If you are bitten by a wild animal, you must consider it a potential rabies exposure unless the animal can be proven not to have rabies.
  • If you see an animal that is acting strangely, stay away and call animal control.

(click image to enlarge and for source)

Putting "One Medicine" into action

People like to talk about the "one medicine" concept. It's a great concept, but my big issue with it is there's a lot of talk but not a lot of action.

One way of thinking about "one medicine" in terms of people and pets is to focus on the health of the entire household as a whole, because:

  • People can transmit infections to pets.
  • Pets can transmit infections to people.
  • People and pets can be infected from the same source.
  • Infection in a pet or person may indicate that others in the household are also at risk.

It's a complex dynamic. When I speak about this topic, I use a couple of different ways to make the point. One is the concept that we are not a population of people living with dogs, cats, horses etc. - we are a population of animals. Similarly, I sometimes say "pets are people too, at least microbiologically." What I'm saying is that we can't focus just on humans or just on pets. The household as a whole needs to be considered, and care of the health of the all of its members - human and animal - needs to considered together.

What does that really mean?

Physicians need to be aware of the presence of pets in the household and other animal contacts. This information might be important when considering certain diseases. For example, if someone comes to their physician with flu-like symptoms and their physician knows they have pet birds (especially psittacines), then the physician would hopefully consider psittacosis. This disease is caused by Chlamydophila psittaci, a bacterium that can be carried by healthy birds. Not realizing there is a bird in the household can lead to a missed diagnosis.

Veterinarians need to be aware of the health status of people in the household. People with close contact with the human healthcare system and people with compromised immune systems are more likely to be carrying certain infectious agents. They are also more likely to pass these pathogens on to their pets. Therefore, knowing the health status of the owner might lead the veterinarian to consider different diseases in the pet, thereby improving diagnosis. Conversely, people with compromised immune systems are at increased risk for various infectious diseases from pets. If the veterinarian knows a pet owner is at increased risk, they can provide better advice about disease prevention measures to protect the owner. Veterinarians rarely ask owners about their immune status, including pregnancy (even the "how far along are you?" question is dangerous, because eventually you're going to get the "I'm not pregnant!" response.) Ideally, people should have a positive, comfortable relationship with their veterinarian, realize that their veterinarian is a member of their (and their family's) overall healthcare team, and therefore tell their veterinarian about any relevant health issues. For this to work, they need to understand the value of this communication, trust their veterinarian and know that their personal details will be kept confidential. At the same time, the veterinarian needs to understand the issues and need for such information, and have a plan on how to use it.

Veterinarians and physicians need to communicate better. They need to know who to contact when necessary and be able to do it efficiently. This is also relevant for non-infectious disease issues. For example, there could be a situation where a veterinarian has had to euthanize a pet: the veterinarian may realize that the owner is quite distraught, but can't do much beyond offering condolences and providing contact information for resources to help them out. The physician may not know anything about the situation, but it could be of significant relevance to the person's health. If nothing else, the physician could be notified that there's a potential concern. There are privacy issues that need to be considered and sorted out, but a little conversation can go a long way. The ability of veterinarians and physicians to contact each other about relevant issues can help prevent problems with miscommunication, provide general information about certain topics and help provide optimal patient care.

One medicine needs to be one medicine in action, not just in theory.

Live every day like you have MRSA

I was giving a talk on infection control at a conference in Geneva a couple of days ago, and during a discussion with someone after the talk, I told them to "Live every day like you have MRSA." Not surprisingly, I got a bit of a strange look in response. I wasn't trying to say, "live your life to the fullest because you never know what will happen." Rather, I was trying to get the point across that healthcare workers in both the veterinary and human systems need to realize that at any point in time they could be carrying MRSA, along with various other harmful microorganisms.

People in patient care positions need to make the assumption that they are always a potential source of disease, and act accordingly while doing their jobs. If someone knew they were a carrier of a bug like MRSA, they'd likely do a better job with routine infection control practices such as handwashing. But, you rarely know whether you're carrying MRSA or not, and it's better to go on the assumption that you are and be diligent with your infection control measures.

The same basic concept applies to different situations, such as how people in the general population behave, and how they interact with other people and animals. In some ways, everyone should assume that they are carrying an infectious disease like influenza, and that every person or animal they encounter is carrying something infectious. (In reality, this is actually true, since everyone is carrying something potentially infectious in or on their body at any given time, it's just that most of the time it's not particularly serious or transmissible organisms).

There's a line between prudence and paranoia, and we don't want to create a population of germophobes who won't leave the house. However, we want to increase awareness so people do a better job of things like washing their hands and covering their mouths properly when coughing or sneezing. Assuming that you and everyone around you is mildly biohazardous maybe a way to do just that.

(click image for source)

MRSA, antibiotics and dogs

When multiple studies report the same results, it gets more and more convincing that the findings are true. This is becoming the case with antibiotic use as a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) infections in dogs. Late last year, I wrote about a study of ours that identified prior antibiotic use as a risk factor in dogs for infections caused by MRSA versus those caused by methicillin-susceptible S. aureus. Recently, a similar study was published, with some similar results. This study (Magalhaes et al, Vet Res, 2010) compared dogs and cats and with MRSA infections to a group of dogs and cats with susceptible infections. They found that MRSA infections were associated with:

  • the number of antimicrobial courses
  • the number of days admitted to veterinary clinics
  • having had surgical implants

Additionally, animals with MRSA infections more often had had contact with people that had been in hospital, but the difference was not statistically significant.

That's two studies that identified antibiotic use as a risk factor for MRSA infection. It makes sense biologically, and it's likely that antibiotic use is an important driving force for MRSA infection in pets (like it is in people).

How do we reduce the likelihood of MRSA infections? It's pretty clear that reducing antibiotic use is a key factor. Antibiotics are important drugs and are certainly needed in many situations, but they're also prone to overuse and misuse. Here are some things that can (and need to) be done:

  • Only use antibiotics when necessary. Antibiotics are often used without evidence of a bacterial infection and in situations where bacterial infections are uncommon (e.g. urinary tract disease in cats, viral upper respiratory tract infections).
  • Use logical and prudent peri-operative antibiotic regimens. Only use antibiotics for surgeries when there are actually needed, and only for as short a period of time as possible.
  • Ensure that proper doses are given (and actually get into the animal). Unfortunately, underdosing (and overdosing) of antibiotics are not uncommon.
  • Promote more research regarding effective antibiotic treatment regimens. We often use much longer courses of antibiotics in pets compared to people, in part because we have no research data telliing us whether we can use shorter treatment courses.

Another thing to consider is the fact that these studies looked at factors for methicillin-resistant versus methicillin-susceptible infections. Therefore, a dog had to have an infection to be included. While certain things are risk factors for MRSA versus susceptible infections, there are other factors that increase the chance of any infection, and reducing these will also help reduce the risk of MRSA (and other) infections (i.e. if your dog doesn't get an infection in the first place, it won't have an MRSA infection).  One very important factor is proper management of underlying skin diseases, such as controlling atopy, flea allergy dermatitis and food allergy. Proper wound care, good veterinary clinic infection control practices and myriad other factors probably also affect the risk of infection in general. Further, good general preventive medicine practices, including overall healthcare and proper nutrition, play a role by decreasing the pet's susceptibility to infections.

Fighting antimicrobial resistance isn't easy or clear cut. There is unlikely a single measures that will turn out to be the "magic bullet." To limit the impact of resistant bacteria, we need to take a multifaceted approach, and we need a lot more information to figure out what specific measures should be emphasized.

Different shelter outbreak, different issues

An Indianapolis area shelter recently put out a public call for foster homes to help deal with an outbreak of respiratory tract disease in cats. They were trying to find homes for sick cats, presumably as part of a plan to depopulate the humane society to help control the outbreak. This is what a lot of people have said that the OSPCA should have done in the recent ringworm outbreak in Newmarket, Ontario. But these are two completely different issues.

The main difference is the nature of the infection. Feline upper respiratory tract viruses only infect cats. Therefore, foster homes that don't have cats can take them safely. Ringworm can affect people and other animals. Every household has some individuals that are susceptible to ringworm. Therefore, cats with respiratory tract infections pose no risk to appropriate foster households, while the same can't be said about ringworm. Reportedly, six staff members and two volunteers have contracted ringworm so far in the Newmarket outbreak.

Fostering a cat with viral respiratory tract disease is relatively easy. You just treat it like any cat and watch for signs of worsening disease or secondary infection. Fostering a cat with ringworm is not as easy. You need to keep it isolated to keep it from spreading the infection through contact with people and animals, and to prevent contamination of the household environment. You need to wear proper protective clothing when handling it. You probably need to treat it, such as giving it a bath twice a week and/or oral medication every day. It's not rocket science, but it takes a lot of time and commitment. Importantly, it takes long-term commitment, since you need to do this for weeks or months. You can't get into a situation when foster homes get bored and want to return the animal before it is considered non-infectious.

In all outbreaks, one of the most important steps is to figure out what happened and why. A detailed (and ideally arms-length) investigation needs to be performed to identify problems with animal management, medical care, general protocol, communications and other areas, and to make any required changes to reduce the risk of it happening again.

Ringworm recommendations

The OSPCA has changed their plans for management of the ringworm outbreak that is ongoing in a Newmarket, Ontario shelter. Now, some (hopefully all) remaining animals will be fostered out to local veterinarians while the situation is being brought under control.

One question that has been asked widely in the press and by the public is why these animals haven't simply been sent to foster homes. Particularly now, with all the attention, there would presumably be many people willing to take in these pets. However, putting animals infected or potentially infected with ringworm into foster homes is a controversial and potentially problematic situation, because ringworm can be spread easily to people and other animals in the household. Sending out an animal that is or may be shedding a zoonotic disease is a tricky situation, and one that can't be taken lightly. Additionally, proper management of these animals can take significant time and effort.

A better approach is to send the animals to places where they can be properly, safely and humanely isolated and treated. Veterinary clinics are a logical option, and a request has been sent to clinics in the area to take animals for quarantine and treatment. The reason veterinary clinics are being solicited is that many clinics have the ability to properly house these animals in isolation units and have the expertise and commitment to properly treat them.

Nonetheless, this is no small favour to ask of these veterinary clinics.  Just as taking an infected pet into a household carries some risk, taking these animals into a clinic is also associated with some risk of transmission to people and other animals. However, with proper facilities and protocols, and the donation of sufficient personnel hours to implement those protocols, the risks should be minimal. To facilitate this, we have developed an information sheet with infection control and treatment recommendations for veterinary clinics. For anyone else who is interested, the document can be found here and on the Worms & Germs Resources page under Information Sheets For Veterinarians.

Image: Ringworm lesions on the paws of a dog. Although this is how "classic" lesions tend to appear, clinical signs of ringworm in pets can be highly variable.  (click image for source)

Why do shelter outbreaks occur?

The recent ringworm outbreak in a Newmarket, Ontario shelter has focused a lot of attention on shelter outbreaks, outbreak prevention and management. A common question that I've been getting in the last couple of days is "Why do these outbreaks occur?"

There are many reasons why an outbreak can develop. I have no first-hand knowledge of the Newmarket outbreak, and don't know what prompted that outbreak, but here are some general causes of outbreaks.

Inadequate protocols:

  • Shelters need clear and logical protocols for all things dealing with animal care. This needs to include aspects like where new animals go, what types of evaluation and monitoring are performed, vaccination and deworming plans, when animals need to be tested or treated, when they can be released from quarantine, how to record and report infectious diseases, how to clean and disinfect areas and items, personal hygiene, and protective clothing, among other things. These protocols need to be in writing and accessible to all personnel.

Inadequate training:

  • Shelters often have large numbers of staff, many with minimal training in animal husbandry or medicine. Proper training is required to ensure that they know what to do and why. (The latter is important because if people know why they need to do something, they are more likely to do it.) Training programs need to be well-structured and formal, not casual, follow-someone-around-and-see-what-they-do training.

Inadequate supervision:

  • Even with good protocols and training, the facility managers need to ensure that protocols are followed. They need to enforce protocols and address problems with compliance. They need to make sure their protocols are up-to-date and consistent with best practices.They need to monitor disease rates and concerning trends of illnesses, so that problems can be identified early. They need to know when to get advice and who to ask (see below).

Infrastructure challenges:

  • Some facilities (or actually, most facilities) are not well designed in terms of infection control. That makes it harder to prevent disease transmission and contain problems. Limitations in isolation/quarantine areas may result in mixing of new (and more likely infectious) animals with those ready for adoption. Few sinks may reduce handwashing, a key component of infection control. A facility that is too small for the animal load results in cramming in too many animals.

Poor awareness:

  • If staff (from management on down) don't understand the issues, they may not act appropriately. Proper routine preventive measures and outbreak response measures may not be convenient, easy or cheap. There must be motivation to implement them. If there is little awareness of the problem, people are less likely to do what is needed.

Failure to act appropriately when the first cases are identified:

  • It is much easier to contain a problem when you act early. If only a few animals have been infected or exposed, it's much easier to take aggressive measures. Once you get a large number of infected or exposed animals, it's much harder to do things like properly separate different groups (e.g. infected vs potentially infected vs non-infected). The more animals affected, the greater the chance of further transmission. Keeping your head in the sand and hoping things will go away can result in a small containable outbreak becoming a facility-wide,  difficult-or-impossible-to-contain outbreak.

Failure to get good advice:

  • People working in shelters can't be expected to be experts in all aspects of infectious diseases and infection control. That's why getting good advice (and following it) is critical. Sometimes, people don't ask for advice or don't go to the real experts. This can happen because they don't really understand the problem, don't know who to contact, don't want to admit they don't know everything or don't realize they are in over their heads. A little good advice, especially early, can make a world of difference.

Bad luck:

  • Ultimately, you can have an exceptionally run facility and still get an outbreak. By the nature of what shelters do, they bring in a lot of animals with potentially infectious diseases and have many animals that are at higher risk of getting sick if they get exposed. It's much less likely to occur with a good infection control program, but you can never 100% guarantee nothing bad will happen. You can't do much about this. All you can do is make the best program possible, and try to limit any problems that develop.

Ringworm at the OSPCA

Never a dull moment...








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Hit by car - How to help and how to be safe

A couple of recent news reports highlight potential issues surrounding good Samaritins helping injured animals:

These two incidents highlight some of the problems that can occur when people try to help injured animals. Wanting to help an injured animal is an instinctive behaviour for many people. I know, I'm the same way - but you have to look after yourself as well.  No matter how much you want to help the animal, you have to make sure you don't put yourself at risk of injury or infection.

The key point is to think before you act.

  • Can you actually do anything useful? Are you better off calling animal control or someone else? In most situations, you may be better off getting other help. If you don't actually know how to help the animal, having contact with it just puts you at risk. Injured or frightened animals are more likely to bite. If you are bitten or otherwise exposed to the animal, you need to be concerned about rabies or other infectious diseases.
  • Can you do something safely? Despite your best intentions, if the animal is in the middle of a busy highway or in a situation where traffic can't see you (e.g. dark, bad weather, blind corner), don't put yourself at risk. You may think that you can be careful but odds are reasonable once you get to the animal, you are going to focus on it, not traffic.
  • Is the animal even alive? This may take a little effort to determine.
  • How is the animal acting? Does it look aggressive or fearful? These things might lead to an increased risk of biting. Is it acting normally? The hard part is assessing injured animals. An animal might be acting abnormally because it's injured. It's also possible, however, that it's acting strange because it has rabies.  It may have been hit by a car because it has rabies, or it may not have been hit at all and just looks like it's been injured because it has severe neurological disease.

If you are bitten by an injured animal, you need to make sure rabies is considered. If the animal survives, it needs to be observed for 10 days to make sure it doesn't develop signs of rabies. If it dies, it needs to be tested. Once you've made the commitment to get involved, you need to follow through.

I'm not trying to dissuade anyone from helping out. You just need to understand what you can do to help and what risks might be present. In most situations, you're probably better off trying to get proper help and trying to prevent the animal from being injured again. Calling animal control, sending someone to a nearby house to identify the owner and trying to make sure other drivers don't hit the animal again may be the best you can do, for the animal and for you.

Rabies vaccination of adopted cats... Why not?

My parents adopted a cat from their local OSPCA shelter the other day. He's an adult cat (maybe named by now, but not at last report) and he came:

  • neutered
  • vaccinated against the typical group of feline diseases
  • dewormed with fenbendazole
  • treated with metronidazole (an antibiotic - it wasn't clear whether this was because he had diarrhea at some point or was diagnosed with something, or whether it was just a routine practice)
  • treated with Revolution for flea control

The one thing that's missing from the list is vaccinated against rabies, which I find amazing. Apparently, the cat was given everything they can give at the shelter without the need for a veterinarian. (Presumably the cat came in neutered, because that would hopefully fall under the "need a veterinarian to do it" category. Prescribing an antibiotic would also be something I'd hope would involve a veterinarian.)

Sending cats to new homes without vaccinating them for rabies is bad practice. Rabies is a rare but extremely serious disease. Vaccination is critical, safe and easy. The OSPCA website says that not all shelters vaccinate against rabies. Some shelters have veterinary staff in the facility, so rabies vaccination would be standard there. Other shelters work with local vets to do this, but that's not universal, apparently. I don't see why this isn't a mandatory policy for the OSPCA. Yes, there is a cost to it, but that should be a cost of doing business. Rabies vaccines aren't expensive and many vets would work with groups like this to keep the costs down. Adopting an animal from a shelter isn't cheap, and recovering the small added cost of the vaccine should be possible. I'm not sure whether it really is a question of cost, accessibility or simply not bothering. Getting a veterinarian involved also has benefits beyond just giving the vaccine. Potential health problems can be identified, including diseases that could be transmitted to people that adopt the animals.

It's true that lack of vaccination of adopted pets can be addressed by getting them vaccinated right after adoption. Any pet that has been adopted (or purchased, or otherwise obtained) should be promptly examined by a veterinarian to identify any potential problems, and to make sure the pet is on a proper preventive medicine program. Realistically though, not everyone does this. While you don't like to set policies according to the lowest common denominator, you need to for a deadly disease like rabies when the consequences to people and pets are so high. I find it hard to justify sending any animal out of a shelter without rabies vaccination.

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Urine collection: Why "pee into the cup" doesn't work for dogs and cats

Urinary tract infections are quite common in dogs. (They're uncommon in cats, but a lot of cats get treated with antibiotics for non-infectious urinary tract disease.) An important aspect of managing urinary tract infections (UTIs) is getting a proper diagnosis. Diagnosing a UTI involves a few different things:

  • Clinical signs: Does the animal have signs that indicate something abnormal is going on in the bladder? This can include frequent urination, abnormal urination, straining to urinate or similar problems.
  • Culture: Can bacteria be grown from the urine sample?


Culture is also something that can be done improperly. If a person has or may have a UTI, that person will usually be asked to collect your own "mid-stream" urine sample by collecting urine into a sterile cup part-way through urination, so that any superficial bacterial contaminants get flush out before the sample is collected. That's not so easy to do in dogs and cats. Collecting midstream free-flow samples into a sterile container without the sample being contaminated by the pets hind end or haircoat, or by the person doing the collecting, is very difficult. A contaminated sample can result in misleading conclusions and potentially inappropriate treatment. Getting a proper sample is critical.

There are two main ways to deal with this problem:

1) Look at the kinds and number of bacteria grown from the urine culture. General guidelines (that are completely empirical) give cutoffs for the level of bacterial growth that should be considered clinically significant versus incidental contamination, with a grey-zone in between. This can be tough to interpret with confidence, so while looking at bacterial numbers can provide some information, it's not the preferred approach.

2) Collection of a sample by cystocentesis. This is a very quick, simple and low risk procedure that involves taking a sample directly out of the bladder using a needle and syringe. The animal is placed on it's back (no anesthesia required, and usually even sedation is unnecessary), the skin is cleaned, and a thin needle is passed through the lower part of the belly, where the bladder lies directly under the skin. Often, if an ultrasound machine is available, a quick check is performed to see the size and location of the bladder, but the procedure can be done without ultrasound assistance.


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Raw diet "research" reports that Nature's Variety, a raw pet food company, has unveiled results of a recent "research study" on their products. Whenever you see "research," especially on the web, you need to consider whether it's really valid scientific information or a marketing ploy. This particular case certainly doesn't seem like anything approaching real research.

Apparently the study, commissioned by Nature's Variety, involved the feeding of six adult dogs variations of different diets over a 4.5 month period. They looked at stool quality, volume and odor, blood chemistry, quality of their skin and coat and body weight.

  • In research, we worry about sample size. You need to have enough animals to detect any real differences. With 6 dogs, 4.5 months of feeding and different diets, you don't have much of a chance to detect a problem (or a benefit, usually). You could have a diet that kills 10% of the dogs that eat it every year and not detect it in study of that size!
  • The number of dogs and time don't even fulfill AAFCO feeding trial requirements, so this doesn't provide any information that would be accepted using standard requirements.

Nature's Variety director of research stated “It’s kind of a sigh of relief.”

  • It's pretty concerning that the head of research would be relieved that there were no obvious health problems in such a small study. If they don't have real confidence in the quality of the food, why are they selling it? If you have confidence in your diet, you say "Of course, as expected, our diet was shown to be nutritious and safe..." not "Wow, we're really happy no dogs died!" Research to indicate safety and nutritional value should be done before you sell, not well after.

Duclos said she expects the study to be published in a peer-reviewed journal in about one year.

  • Not likely. For one thing, from what they are releasing, it's very weak and not defensible scientifically. For another, they've already released the results. It's inappropriate for people to release results before they've undergone peer review, and releasing data in a press release will probably prevent any reasonable journal from even considering the study.

It's good that Nature's Variety is trying to do some research. It's also good that they're addressing Salmonella contamination following their recent recall. The fact that they are doing something progressive is an encouraging sign. However, they need to do proper research, and make sure it undergoes appropriate scrutiny, instead of using small and relatively useless studies to generate press releases.

Raw feeding has inherent risks of exposure for people and pets to potentially harmful bacteria like Salmonella. Raw feeding can probably be done safely for both the pet and people in some, but not all, situations. More information about raw meat feeding can be found on the Worms & Germs Resources page. 

Click image for source.

Raw food recall expanded

Nature's Variety has expanded their recall based on more concerns about Salmonella contamination of their products. In a lot of ways, this makes no sense to me since you have to assume that raw meat is contaminated with Salmonella, E. coli, Campylobacter and various other pathogens. That's been clearly shown in studies of raw meat for humans and animals, and that's why we cook meat intended for human consumption and emphasize good food handling practices. It's also why there are concerns about feeding raw meat to pets, and the explanation for various studies showing pets fed raw meat have much higher rates of shedding potentially harmful bacteria like SalmonellaYou have to assume that a reasonable percentage of Nature's Variety's food has been contaminated with Salmonella, not that this is an uncommon and preventable event.

Because of the problem or consumer concerns, Nature's Variety has announced that they will be treating all of their diets using high pressure pasteurization. Basically, this process uses very high pressures (with only a slight increase in temperature) to reduce bacterial levels. I can't find any scientific literature about the effectiveness of this method on Salmonella contamination of raw meat (it's mainly used with milk and cheese) but it should be able to greatly reduce bacterial levels in meat. That's a good thing, as long as it works. What's important to know, however, is whether it is really highly effective in this situation and whether all potentially harmful bacterial will be eliminated every time.

I'm concerned that if people think this food is "sterile" and it's not, they might not take the necessary food handling precautions. If this method usually, but not always, kills all of the bad bacteria, or if it reduces levels greatly but not completely, then there could still be the risk of infection of people and pets. This information is critical. In the absence of clear scientific data, I think we need to assume that some level of contamination could still be present (although probably much less often and at a much lower level), and make sure that proper food handling practices are used.

It's good to see this company taking measures to reduce the risks associated with raw meat feeding. Let's hope that some objective research is made available to indicate what risks might remain.

Image source:

2009 feline H1N1 case published

When the novel H1N1 influenza pandemic infected large numbers of people, it was not particularly surprising that the occasional infection was noted in pets, considering over 50% of North American households have pets, and the close nature of contact that many people have with their pets. While the few cases that occurred were highly publicized, in the end pet infections were rarely diagnosed (although that doesn't mean they were truly rare), and limited information about these cases has been available. Details regarding one H1N1-infected cat from Iowa (Sponseller et al. 2010) were recently published in Emerging Infectious Diseases.

Here are some of the highlights:

  • The 13-year-old cat was an indoor cat that was admitted to Iowa State University's veterinary hospital because of depression, decreased appetite and signs of respiratory disease.
  • Two of 3 people in the house had undiagnosed influenza-like illness a few days before the cat got sick. The cat was an affectionate pet and interacted closely with household members.
  • Influenza was diagnosed in the cat by detection of H1N1 influenza virus using molecular diagnostic methods (reverse transcriptase PCR) on a sample of fluid collected from the lungs.
  • The cat improved with supportive care alone (mainly intravenous fluids to correct dehydration).

Considering the cat lived indoors and people in the house had signs consistent with influenza, it's almost certain that the cat was infected by its owners. This isn't surprising, but it's a good example of how infectious diseases can move between people and pets, in either direction. There's no evidence that pets were a source of human infection, but if something can move from people to pets, there's certainly good reason to think that it could go back from pets to other people. This should be another wake-up call for the need to consider and investigate the potential role of pets in any emerging infectious disease, and to consider emerging "human" diseases in sick animals that might have been exposed.

Composting pet waste

An article in Saturday's Toronto Star discussed composting options for people without organic waste pickup or the ability to have a backyard composter, including indoor composters that can be used by apartment or condo dwellers who want to satisfy their eco-friendly side.

They mentioned that one of the composters they highlighted (NatureMill) can apparently handle pet waste, but composting animal feces is not a good idea. Pet waste (feces +/- cat litter etc.) can contain a wide range of potentially harmful parasites and bacteria. The composting process can generate enough heat to kill these bugs, but it's not guaranteed to do so, and I'd be especially concerned about small indoor composters. Having a few nasty things in the composter itself isn't necessarily a big deal, but what happens down the line? People can be exposed to these microorganisms when removing compost, and (maybe more importantly) compost usually ends up in gardens where the bad bugs can contaminate the soil, as well as anything grown in the garden.

One concerning microbe is the protozoal parasite Toxoplasma gondii. Cats are the natural reservoir of Toxoplasma and can pass it in their feces (usually only for a short period), but most people that become infected by Toxoplasma are likely exposed to the oocysts ("eggs") outside in gardens, or from contact with contaminated foods (e.g. unwashed vegetables). (Undercooked meat can also be a source of infection, but that's another story).  Composting may not kill this parasite, so when pet-waste compost is put into flower gardens or vegetable gardens in which people work, the risk of exposure to Toxoplasma may be increased. The risk of transmission from an individual cat is admittedly low, since only a very small percentage of cats are shedding the parasite at any one time (even though most have at one point), but it's a preventable risk. There are also various other microorganisms that are potential concerns. While composting is a great way to dispose of most organic wastes, it's best to keep putting dog and cat feces in the garbage or down the toilet (and wash your hands afterward, of course).

If you really feel the need to compost pet waste, the safest alternative is probably to have a separate composter for pet waste that you handle a bit differently: pay careful attention to hand hygiene after handling the compost, and make sure the compost isn't used in gardens or other areas where people might have contact with the soil.

Click image for source.

Ear mites and the strange pursuit of knowledge




Personally, I think I would have stopped there. (Actually, I wouldn't have made it to that point, but if I did, I certainly wouldn't have tried it again.) Yet, Dr. Lopez wanted to confirm his findings so, a few weeks later, he infected himself again with mites from another cat. The same type of disease developed, although it was less severe and only lasted two weeks.


Self-experimentation is generally frowned upon, but has been the source of remarkably scientific discoveries, even Nobel Prize winning discoveries (e.g. the role of Helicobacter pylori in gastric ulcers in people). I don't think Dr. Lopez is in line for any prizes, but it shows how a little academic curiosity along with minimal squeamishness can provide some interesting information.

What's the relevance of all this? If your pet has signs of ear mite infestation (e.g. scratching at the ears, dirty material inside the ears), get it examined and treated. If nothing else, this needs to be done because it's a very uncomfortable problem for the pet. There's also some risk of human infection, but it's probably minimal. The mites have to make it from the pet's ear to your body to cause problems. The quicker they are treated, the lower the likelihood of this occurring. Human ear mite infestations, be they in the ear or on the skin, seem to resolve by themselves, with treatment of the animal being the most important part of control. However, it can be a pretty uncomfortable condition and one most people (with the possible exception of Dr. Lopez) would certainly rather avoid.

Raw food recall: Salmonella

Nature's Variety has recalled chicken-based raw meat products because of Salmonella contamination. After a customer complaint about "digestive problems," they tested the food and found Salmonella, prompting the recall. (For more details about the recall, click here.)  In some ways, this doesn't make a lot of sense to me. If you think Salmonella contamination should be an uncommon event and a problem, you should test routinely, not wait until animals get sick. If you think that Salmonella contamination of raw meat is expected (which it is), then why test or recall? Just assume that every raw meat sample is positive for Salmonella (and Campylobacter, and E. coli). Recalling raw meat for Salmonella isn't logical. Presumably, a large percentage of the raw meat that they have sold and which they will sell in the future is contaminated, based on various studies of commercial raw meat. Handling and feeding raw meat carries an inherent risk of human and animal infections with Salmonella, Campylobacter, E. coli and other bacteria. People that feed raw meat need to understand that risk, and consider whether it's a reasonable risk for their pets and the people in the household. I don't think feeding raw meat is a good idea, but in some situations it's a particularly bad idea (e.g. when there are infants, elderly persons or immunocompromised people in the household, when the pet is very old or very young, when the pet visits high risk people).


Musings about antibiotic therapy in dogs and cats

I recently attended a meeting to develop antibiotic use guidelines for dogs and cats. One recurring theme during the discussions was our paucity of scientific evidence about how to use antibiotics in certain situations. It's really interesting when you compare antibiotic treatment regimens that are used in humans and standard practices for dogs and cats. Almost invariably, we treat dogs and cats for much longer periods of time than people, even when very similar diseases are compared. Why is this?

One reason is a lack of people doing research and the difficulty performing (and funding) the large clinical trials that are needed to evaluate different treatment protocols. For example, we tend to treat urinary tract infections in dogs for 7-10 days, while in people, just 3 days of treatment is much more common. However, longer treatment courses were used in humans until various research studies showed that shorter treatment was as effective and had fewer side effects. It's likely that we could treat urinary tract infections in dogs for shorter periods of time but we don't have the data to support it at this point.

It's possible that longer treatments for certain conditions are indeed needed in dogs and cats compared to humans. An argument to this effect is that disease in pets can often be more advanced (and therefore potentially harder to treat) when first detected than similar disease in people. For example, if someone has a urinary tract infection, they are probably going to get to their physician quickly. Many owners may not notice the signs of an infection in their pets as early. More established infections may take longer to treat. Does that really happen? We don't know, but it's something we need to know to determine proper treatment durations.

"If it ain't broke, don't fix it". This isn't a very good philosophy when it comes to medicine but it's understandable. If a certain treatment plan usually works, people are hesitant to look at alternatives. The problems with longer term therapy, such as adverse effects of drugs and development of antibiotic resistance, are not necessarily considered (but they need to be).

Bottom line: We need good research to determine optimal treatment protocols for pets. It's very likely that we can greatly decrease the amount of antibiotics that we use while improving patient care, but without good evidence, it's hard to know what to do and where to start. Being too aggressive and dropping treatment times in the absence of evidence may not be a wise decision - too short a treatment period could result in treatment failures and ultimately more sick animals and overall more antibiotic use.

Click image for source.

More on pets and the risk of MRSA

We've seen reasonably good evidence of the potential involvement of pets in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) for a few years, and a study recently published in the Journal of Hospital Infection (Loeffler et al 2010) sheds a little more light on the subject.

In this UK study, they tested 608 veterinary staff and pet owners in contact with pets that were carrying MRSA or methicillin-susceptible S. aureus (MSSA). MRSA carriage was identified in 12.3% of veterinarians that treated MRSA-infected animals and in 7.5% of their owners (although the chicken vs egg conundrum comes up, i.e. are vets that treated MRSA -infected pets more likely to have MRSA because they got it from the pet or because they already had MRSA and infected their patient?). These numbers are relatively consistent with a small number of other studies that have looked at these groups, and are higher than the expected carriage rates in the general population. This is highlighted by the results from people that had contact with animals only carrying methicillin-susceptible S. aureus, since MRSA was only identified in 4.8% of veterinary staff and 0% of owners in this group. Veterinary personnel were significantly more likely to carry MRSA than pet owners. As expected, virtually all MRSA from people and pets in the study were the predominant strains present in human hospitals in the UK.

We shouldn't fear MRSA or our pets, but we should respect the potential for infection and act accordingly. Mainly, this involves basic practices like:

  • Good hygiene: washing hands regularly after handling pets
  • Avoiding contact with infected body sites in pets, and preventing pets from having contact with infected body sites in people
  • Prudent antibiotic use in both veterinary and human medicine
  • Proper and timely diagnostic testing to identify MRSA infections, to permit proper treatment and earlier implementation of appropriate infection control practices.

Ultimately, MRSA in pets is a human-borne disease. Most pets that have MRSA presumably acquire it from a close human contact, so efforts at controlling MRSA in pets need to be directed at both the pet and human aspects. Uncontrolled MRSA in people will lead to increased risk for pets, and for pets to be a source of subsequent human infection.

Image: Seven-month-old British Shorthair (photo credit: Tamila Aspen)

Hepatitis C and cat scrathes

I had an advice call recently about the risk of hepatitis C transmission by cat scratches. Hepatitis C is a human virus that can cause serious liver disease. It is most commonly transmitted via the blood of infected individuals. The concern with cats in this case was whether there is a risk of transmission if a cat were to scratch someone with hepatitis C and then scratch someone else.

There are no reported cases of hepatitis C transmission via a cat scratch. For transmission to occur, the following must happen:

  • The cat must scratch an infected person who has hepatitis C virus circulating in their bloodstream.
  • The scratch must draw blood, which then contaminates the cat's claws.
  • The virus must survive on the cat's claws.
  • The cat must scratch someone else deep enough to draw blood.
  • Hepatitis C virus must go from the cat's claws into the person's bloodstream and survive.

The odds of this sequence happening are very low. It's similar to the concerns about HIV transmission from dog bites - theoretically possible, never proven, and probably of very little concern.

This could be seen as similar to the situation with needlestick injuries in people: someone draws blood from an infected person, and then promptly sticks his or her finger with the needle by accident. Hepatitis C is not efficiently transmitted by needlesticks; only about 1.8% of people that get stuck in this manner (with a needle contaminated with blood from a hepatitis C-positive individual) develop antibodies against the virus. The risk is highest with hollow-bore needles (such as those used for injections and blood sampling) compared to needles used for sutures, because of the greater volume of blood that could be transferred via a hollow-bore needle. Cat scratches are presumably more like surgical needle punctures - there can only be contaminated blood on the outside of the claw, not inside it.

The only time I might have any concern would be if I suffered a significant scratch injury from a cat that had immediately before that caused a major injury in a hepatitis C-positive individual, such as in a situation that might be encountered when two people were breaking up a cat fight, or when someone was trying to pry an attacking cat off another person. It's a very unlikely scenario, and the associated risk would still be extremely low.

Bottom line: Don't worry about hepatitis C when around cats and infected people. Use common sense measures to avoid being scratched at all times.

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Rabies quarantine in (and of) Santa Cruz County, Arizona

A large number of rabies cases in Santa Cruz County, Arizona has lead to the rare practice of implementing a county-wide rabies quarantine. Fifty-four cases of rabies have been diagnosed so far this year, mainly in skunks. That's about twice as many as normal.

Quarantine is probably not the best description of what they are doing, but they are taking measures to improve vaccination of pets, reduce roaming pets and discourage human-wildlife interaction.

For the next 60 days, the following rules are in place:

  • Dogs and cats must be vaccinated against rabies.
  • Dogs must be confined to the property or on a leash.
  • People are not allowed to feed wild animals.
  • Pet food must not be left outdoors after sundown.

Those are all pretty standard measures that should be used anytime. It sounds like these rules already exist in Santa Cruz County but their "quarantine" means that they will be aggressive in enforcing them. Increasing enforcement is a good idea, but ongoing efforts after this quarantine period are also needed because rabies will continue to be a risk in that area.

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Feline leprosy

Leprosy usually evokes images of deformed faces and hands and leper colonies. This disease, caused by Mycobacterium leprae, has been recognized for at least 4000 years, and is thought to have been one of the biblical plagues. While now treatable with proper access to healthcare, leprosy is still a problem in some regions.

Feline leprosy is a disease that is present in cats in certain areas of the world, especially British Columbia Canada, northern New Zealand and eastern Australia. It typically causes granulomas (firm fleshy, tumour-like masses) in the skin and tissues directly under the skin, These can become ulcerated and secondary bacterial infections can develop. Feline leprosy has some similarities to human leprosy, however it's not the same thing. It is caused by a related but distinct bacterium Mycobacterium lepraemurium. (It's also suspected that one or more other related bacteria can also cause this disease.) Mycobacterium lepraemurium also causes disease in rodents and can survive in the environment. Cats most likely become infected after being bitten by infected rodents. While the name may be concerning and the disease can be serious in cats, fortunately there is no risk to humans. There is no evidence that this uncommon disease in cats can be transmitted to people.

Image: A photomicrograph of Mycobacterium leprae taken from a leprosy skin lesion. (source: CDC Public Health Image Library ID#2123).

Probiotics and obesity

A recent editorial in Nature Microbiology Reviews by Dr. Didier Raoult raised questions about the potential role of probiotics in obesity.  It is based both on studies indicating weight gain in humans and farm animals in probiotic trials as well as some laboratory animal data. The conclusions based on clinical trials for treatment of disease are pretty weak, since while animals or people may have gained weight, that does not mean they gained fat (if you get better because of a probiotic, you gain weight, but that is probably a healthy response and not obesity). There is some interesting lab animal work that shows changes in fat deposition in response to some probiotics, but it's rather preliminary.

It's way too early to declare that consuming probiotics is a risk factor for obesity. Several letters to the Editor were submited by leading probiotic researchers in response to Dr. Raoult's editorial, contradicting some of the statements that were made. Personally, I don't see convincing evidence of a risk but Dr. Raoult's comments should serve as a reminder that probiotics can have broad and poorly understood effects on the intestinal bacterial population, and correspondingly broad and poorly understood effects on the body. That's why probiotics should be scrutinized like drugs, in terms of safety, effectiveness and quality control. If someone is using a probiotic for themselves or their pet for a defined reason and it seems to be working, I wouldn't recommend stopping because of these largely theoretical concerns about obesity. However, we should perhaps think about why we are using probiotics and the potential costs versus benefits. I doubt this is really going to be a major issue but it's a good one to think about.

Campylobacter upsaliensis: an overlooked problem?

Campylobacter bacteria are important causes of disease in people. Many Campylobacter species exist, and these different species vary quite a bit in their ability to cause disease in people and animals. Campylobacter jejuni is one of the most common causes of diarrhea in people worldwide, and is most commonly associated with contaminated food.  However, a few studies have reported that having pets (especially pets with diarrhea) is also a risk factor for Campylobacter jejuni infection.

Another Campylobacter species that may be of concern is Campylobacter upsaliensis. This species is primarily associated with dogs and cats, and a large percentage of healthy dogs and cats may be shedding this bacterium in their stool at any time. It doesn't seem to be a cause of disease in dogs and cats, but it may be an important and overlooked cause of disease in people. One study from the US reported that C. upsaliensis was the 2nd most common Campylobacter strain found in people with diarrhea (after C. jejuni). However, the true role of this species is unclear, partly because of common laboratory testing methods. Culture is the main method used to diagnose infection with Campylobacter, but this bacterium can be difficult to grow in the lab. Usually, culture media for Campylobacter contain antibiotics to inhibit other better/faster growing bacteria. Unfortunately, C. upsaliensis is often inhibited by these antibiotics, so it's likely to be missed in these cases even if it is there. Therefore, we might be underestimating the role of this Campylobacter species in diarrhea. This is an critical issue to investigate because C. upsaliensis is so common in dogs and cats, and it's important to determine what role pets play in human disease.

Avoiding Campylobacter infection involves some basic steps: avoid contact with feces, take care when handling diarrhea from pets, wash your hands regularly after handling pets and always wash your hands thoroughly after any contact with feces. Make sure your physician knows you have pets. In particular, if you have a pet with diarrhea or have recently acquired a new pet (especially a puppy or kitten), make sure Campylobacter infection is considered if you get diarrhea. Most infections are mild and go away on their own but some require specific treatment.

More information about Campylobacter can be found on the Worms & Germs Resources page.

Image credit: CDC/ Dr. Patricia Fields, Dr. Collette Fitzgerald

More H1N1 cat cases

Perhaps not too surprisingly, more cats have been diagnosed with H1N1. Following the first reported case in Iowa, two more cases have been reported: one in Utah and one in Oregon. The Utah case apparently had typical flu-like disease. The cat from Oregon died of severe respiratory disease.

This doesn't really change anything. We know cats are susceptible, although not highly so considering the small number of cases despite large numbers of cats being exposed by their owners. H1N1 in cats is a human-associated disease, with cats getting infected from infected people. We still have no evidence that pets are a source of human infection. Even so, good general hygiene practices should be used around infected pets and people to reduce the risk of transmission in both directions.

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Stray cats and H1N1 influenza

The topic of the potential for feral (stray) animals, particularly cats, to be sources of human influenza infection came up today. For feral animals to be a public health problem, the following sequence has to happen:

Feral animals need to be exposed to H1N1

  • This is pretty unlikely. Influenza is spread through close contact, mainly through aerosols generated by an infectious person coughing, sneezing or breathing. Influenza only travels short distances in this manner. The likelihood of a feral animal being exposed to the H1N1 influenza virus is very low because it is rare for a feral animal to get that close to people. If there is close contact, it's probably very short term, and not high risk for exposure.

They need to become infected AND shed appreciable levels of virus

  • Considering the number of infected people, how common pet cats are, and the fact that only one cat has been diagnosed with H1N1, the risk of actually transmitting the virus to a cat is very low even with close contact with an infected person. If tens of thousands of household pet cats have had close and prolonged exposure and only one infection has been diagnosed, this virus is pretty poorly transmissible to cats.

They need to be exposed to susceptible people

  • As discussed above, there's not too much contact between stray cats and people. Close and prolonged contact is extremely rare. Influenza is only shed by infected individuals for a short period of time, unlike some other infections. So, the chance of an infected cat having close contact with a person during the relatively short infectious period is very low.

Each one of these events independently is very unlikely. When you combine them, it should be clear that the risks posed by feral cats are extremely low (probably about as close to zero as we get with infectious diseases).

A bigger concern might be someone infecting their indoor/outdoor cat, who would then infect a stray cat, which would then infect another indoor/outdoor cat, which could infect a family member. That's still a VERY unlikely situation - really it's nothing to worry about.

There are certainly public health issues with feral cats. H1N1 is not one of them.

H1N1, cats and the potential for mutation

I've spent a lot of time talking to the press this week about H1N1 and pets. One question that has come up repeatedly involves concern about the potential for this virus to mutate because of its presence in pets. This largely relates to the general knowledge that pigs are potentially important "mixing vessels" for influenza viruses.

H1N1 infection of cats carries almost no risk of a significant mutation. For this to happen, the animal must be infected with two different influenza viruses, and those viruses must recombine so that a new virus containing parts of each of the parent viruses is produced. This virus must then be able to infect a new host and be transmitted. Pigs are a concern because they can be infected by various influenza viruses (from humans and birds, as well as swine-origin viruses), and they tend to live with many other pigs so that the transmission cycle can be started. This isn't the case with cats.

Cats don't have their own influenza virus that is in circulation. Therefore, it's very unlikely that a cat exposed to H1N1 already has a different influenza virus in its system. Even if a cat was infected with a different flu virus (which is exceedingly unlikely) and this virus recombined with H1N1 (which is unlikely even if the two viruses were present), your average cat doesn't have much contact with different individuals, human or animal, and it's quite possible that the virus would just die-out in that animal.

While we don't want to ignore some of the issues regarding H1N1 in pets, such as the potential for pet illness and the unproven possibility that they could transmit H1N1 to other people, we need to keep the concerns in perspective. The risk that pets pose to people is much lower than the already very low risk that people pose to pets, in terms of H1N1 influenza.

How to diagnosis influenza in pets

One of the common questions accompanying the onslaught of calls I've taken today is "How do you diagnose influenza in pets?"

Clinical signs, such as sneezing, coughing, fever and lethargy, are not useful for diagnosis. Influenza can produce highly variable disease, ranging from almost none to very severe - so you can't look at an animal and say it has influenza just based on the clinical signs. We don't know much about H1N1 influenza in different animal species (including pets), but this type of influenza can probably cause a wide range of disease in animals as well (at least in those it can infect).

The presence of someone in the household with influenza should get you thinking about flu in a sick pet, but it is far from diagnostic. Many, many people have influenza, but very few pets do. There are many other diseases that can produce signs similar to influenza in pets. The health of people in the household is an important thing to know, but we can't jump to conclusions based on the household history alone.

Laboratory testing is required for the diagnosis of influenza, and there are a few options:

  • PCR testing of nasopharyngeal (throat) or nasal swabs, or fluid collected from the trachea: This molecular test detects influenza virus RNA. This is the fastest test and it is most sensitive when samples are taken early in disease. This is the main option for diagnosis at this time.
  • Serology: This involves testing blood for antibodies against influenza. Two samples are taken 10-14 days apart. If the antibody level rises 4-fold or greater, that is indicative of influenza infection. This is considered the most reliable method of diagnosis of influenza in many species but takes time. It is not currently a viable option for pets because tests for pets are not available.
  • Virus isolation from nasopharyngeal or nasal swabs, or tracheal fluid: Samples are inoculated into eggs to try to grow the virus. This can take quite a while and isolation of the virus can be difficult. This is a method used by specialized labs with laboratory containment conditions appropriate for this virus and may not be readily available.

H1N1 in a cat

H1N1 influenza has been confirmed in a cat in Iowa. The cat had "influenza-like illness" and was tested, with H1N1 being confirmed today. Two of three people in the house were also sick, but they became ill before the cat, and were presumably the source of infection for the cat. There's no evidence that the cat has infected anyone.

This doesn't really change anything that we've been recommending regarding H1N1 and pets. H1N1 infection is pets is rare but has been diagnosed in ferrets, and now in a cat. Considering the large number of infected people and the presumably large number of exposed pets, the risk of transmission to pets appears to be extremely low. Low doesn't mean no, however, and taking basic precautions is still wise.

Basically, remember that your pets are part of the household - microbiologically as well as socially. If you are doing something to reduce the risk of transmission of infection to people in the household, act the same way around your pets. Reduce contact with pets if you are sick. Avoid being around them when you are coughing. Wash your hands frequently. Avoid contact with their faces. If your pet gets sick after you've had H1N1 (or any other infection) make sure your veterinarian is aware of it.

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Pets and H1N1 revisited

The recent discovery of H1N1 influenza in a pet ferret has led to another round of concern about the potential impact of H1N1 on pets and pets as a source of human infection. Finding H1N1 in a ferret is not particularly surprising, considering ferrets are susceptible to various (including human) influenza viruses. We shouldn't dismiss the potential that certain pets could become infected by this virus or transmit, it but the overall risks are presumed to be very low. There have obviously been many, many cases of H1N1 influenza in pet owners, yet there is just this one report in a pet (although it's certainly possible that other pets have been infected but not diagnosed). Ferrets may be the biggest concern. Pet birds and pot-bellied pigs may also be at higher risk considering this virus can clearly infect pigs and birds. Cats are probably a bigger concern than dogs because of what we know about cats' susceptibility to (and ability to shed) H5N1 (avian) influenza.

The risks are low to pets and pet owners, but there's rarely a no-risk situation with infectious diseases. A few basic measures should be taken to reduce the risks associated with this pandemic virus:

  • If you have (or think you may have) influenza, treat you pet like other people in your family. Avoid contact with them, especially their faces, and pay close attention to hygiene (especially handwashing). This should help reduce the risk of exposing your pet to H1N1.
  • If you have influenza, or your pet has been exposed to anyone with influenza, and your pet becomes ill (e.g. respiratory disease, fever, lethargy), contact your veterinarian. Avoid close contact with your sick pet (especially the face) and wash your hands after you handle it.
  • Relax and enjoy the company of your pet. The risks of influenza are low.

Rabies and roadkill

Here's a recent question: "Can a rabies virus get into the body if you pick up a dead animal the roadway and have a cut on your hand? I understand the animal has to carry the rabies virus but sometimes we don't know what killed the animal. It may be infected and didn't use due diligence or perhaps it just wasn't fast enough. After reading stories here I'm less likely to remove a dead animal. Sometimes they are so juicy, the fluids are flung about and you may get some on your clothes or skin and not know it. How likely is contracting rabies from fluids in a cut? The reason I ask is when I was younger I picked up a dead squirrel with my bare hands and then noticed I had cuts on my hands. I went to a doctor who looked at me like I was crazy but I had that uneasy feeling because I knew rabies is almost always fatal. Of course, I didn't get it but when I watch other people remove dead animals from roadways I cringe. I can't even think about eating roadkill or skinning it for the fur but that's just me."

Good question. You've covered most of the important aspects of risk, which are pretty minimal:

  • Animal has to be infected
  • Live rabies virus needs to be present
  • Rabies virus needs to get into a person's body (not just on it)

Let's look at these individually.

Animal needs to be infected

  • You never know whether this is a concern when you find a dead animal. Once it's dead, you can't tell if it's acting strange. In general, it's safest to assume that all such animals are infectious until proven otherwise.

Live rabies virus needs to be present

  • I haven't come across good information about how long rabies virus can survive in a dead body outdoors.  It probably varies greatly between different situations, particularly depending on the temperature of the body. For very fresh roadkill, there's certainly a possibility that live virus is still present (if the animal had rabies).


  • Rabies cannot be transmitted through intact skin. Rabies infection is transmitted mainly through bites, cuts and scrapes. Saliva or nervous system (e.g. brain) tissue are infectious. Blood, urine and feces are not.
  • If you have contact with a dead animal, avoid any direct contact with your skin, and avoid any activities that could result in splashing of fluids. Transmission of rabies from infected fluids is possible if it comes in contact with broken skin or mucous membranes like the eyes or mouth.
  • If intact skin has been contaminated with fluid, wash it thoroughly with soap and water, but don't panic - it's really of minimal concern.
  • If your clothes have been contaminated with fluid, take them off right away if possible.  If that's not practical (or legal), take them off as soon as you get home. Put them in the laundry immediately and wash your hands.
  • If open sores or other broken skin has been contaminated, wash the area thoroughly with copious amounts of soap and water under moderate pressure. Disinfectants can be used to help clean the wound, but there's no consensus about whether that's necessary - these chemicals can be painful to use and hard on tissue, and the flushing action of the water probably does the most to remove the virus from the area. You should go to a physician, who will get in touch with public health personnel to determine if there is any reason for post-exposure treatment.  If the animal's body is available to test, that's useful. If the brain has decayed too much to be tested properly, it's questionable whether live rabies virus would still be present even if the animal had rabies.  Public health personnel will decide whether they think there is any risk.

Bottom line: the risk of contracting rabies from roadkill is very low. Roadkill contact has never, to my knowledge, been identified as a source of infection. Rabies transmission from dead animals has been documented, however, such as a couple cases of rabies from people preparing dead animals for food.

So, if you see a dead animal by the road, leave it alone. If you are going (for some reason) to touch it, first make sure it's really dead. An injured animal might be much more likely to bite. If it's really dead and you are just trying to move it off the road, use a stick, shovel or something else that doesn't involve you having direct contact with the animal. Other than that, I'm not sure why anyone would want to touch roadkill.

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How do you disinfect a cat?







Rabies in vaccinated dogs and cats

A study in the Journal of the American Veterinary Medical Association (Murray et al 2009) investigated the rabies vaccination history of dogs and cats diagnosed with rabies in 21 US states between 1997 and 2001. 

  • 264 rabid dogs and 840 rabid cats were identified.
  • 4.9% of rabid dogs and 2.6% of rabid cats had a history of rabies vaccination.
  • Of the 13 dogs that had been vaccinated, only 2 were considered currently vaccinated. Similarly, of the 22 previously vaccinated cats, only 3 were currently vaccinated.
  • Texas had the most positive dogs while Pennsylvania had the most positive cats.

This study cannot determine how effective vaccination is. You'd need to know the number of animals that were and were not vaccinated, and then the number that did or didn't get rabies to determine efficacy. The fact that a small number of properly vaccinated animals got rabies shows the vaccine is not 100% protective, which is not surprising.

Vaccination is an important part of rabies prevention, but it's not the only part. Vaccination is a last line of defense - avoiding exposure to rabies is the critical first line. To reduce the risk of rabies exposure, keep your pets under your control at all times. Keep bats out of the house and try to ensure that your house and yard are not welcoming to wild animals. Don't let your pets have contact with wildlife and pay close attention when strangely-acting wildlife are around. Active measures to reduce wildlife rabies such as rabies baiting are also important.

Don't assume because your pet is vaccinated that you don't have to worry about trying to reduce the risk of exposure to rabies.

Don't assume that an animal with neurological disease doesn't have rabies just because it's been vaccinated.

"Family protection" screening of healthy pets

As public awareness of zoonotic diseases increases, some new marketing opportunities are created. One is offering screening of pets for "protection" of the family. One company, Healthgene, offers a Family Protection Program that involves screening pets for selected zoonotic pathogens. Unfortunately, it involves the use of non-validated PCR tests for pathogens for which screening of healthy animals is not considered useful. They make various unsupported, illogical and sometimes downright incorrect statements such as "If, by chance, any positive results should occur, not only should the animal be treated immediately, but the client and anyone having contact with the animal should also notify their family physician." Despite the fact that the tests themselves are of questionable quality and the results are essentially useless, I'm sure they are developing a market.

Also, it's pretty concerning that this company misspells the names of various microoganisms for which they test on their website - they even misspell "protection" in one of their Family Protection Plan info sheets! Inability to spell isn't necessarily linked to inability to test properly, but it shows a lack of care and attention to detail that raises further red flags in my mind.

Zoonotic diseases ARE a concern. We need to pay attention to them and try to reduce the risks of transmission to people. Screening healthy animals is almost never a component of this. Save your money when it comes to "routine" screening of healthy animals - talking to your vet about potential problems and washing your hands are much better ways to reduce the risk of infection.

The "Truth" about vaccinations?

Norfolk, VIrginia's has an article entitled "The Truth About Pet Vaccinations". It's basically the same as hundreds or thousands of other articles available on the internet purporting to try to set the unwary pet-owning public straight about pet vaccines. Here are some of the highlights.

The evidence against vaccinating, however, is overwhelming.

  • What evidence? Someone's commentary? Sure, there are hundreds of those. Real scientific proof? Nope. No one is going to dispute that vaccine reactions and other problems can occur. That's clear. At the same time, vaccines clearly save lives and reduce illness. There is certainly a cost-benefit to consider, but non-evidence-based statements like this don't help. The risks and benefits do need to be considered when designing a vaccination program. Real evidence should be used, however.

It is more and more common to see cancer in dogs and cats under 5 years of age.  Autoimmune diseases are on the rise as well.

  • Maybe, although you have to be careful interpreting that. We have much better diagnostic tests now and can detect diseases we couldn't diagnose before. Also, animals that are alive because they didn't die of an infectious disease are able to develop these conditions.  You cannot simply attribute such a trend to modern vaccine practices without looking at the other factors that may be involved.

Vaccinations do help prevent serious illnesses, but they should be used with restraint.  Before vaccinating, consider the risk.

  • Absolutely. Best piece of advice in the article.

If your cat is indoor only and will never be exposed to unvaccinated animals, the risk of infection is low.

  • While the risk of exposure is LOWER for indoor cats, it's not zero. It's amazing how many "indoor" cats come into vet clinics after being hit by a car or getting into a fight with a wild animal. Indoor cats can escape. Also, other animals can get inside, particularly bats - a source of rabies exposure.

Request individual vaccines and vaccinate at least three weeks apart if possible.

  • There's little to no evidence that using combination vaccines is a bad thing for your average pet. Also, individual vaccines aren't available for all diseases. Further, if you only vaccinate for one disease at a time and space them three weeks apart, it's going to take a longer time to have an animal with protective immunity. It makes it a lot more expensive too.


  • This sentence should start at "give."  Every animal in an area where rabies may be present must be vaccinated, regardless of whether it goes outside.

Vaccinations do not need “boosting”

  • Says who? This is a generalization that can cause problems. For some vaccines in some animals, a single dose may be adequate, but it's certainly not true for all. Some vaccines work better than others. Some diseases are more amenable to good vaccination prevention. Some vaccines are probably good for a long time, if not life-long. But not all of them.

Simple blood tests can determine if your companion’s antibody levels for parvovirus and distemper remain high enough to resist infection.

  • Nope. You can determine antibody levels but no one really knows how to interpret them (i.e. what level means the animal will be protected). Antibodies are only one component of vaccine protection.

The currently licensed leptospira bacterins do not contain the serovars causing the majority of clinical leptospirosis today, so it is generally not a useful vaccine. 

  • That's true for certain areas. In some regions, the vaccines strains are protective for the strains causing disease.

Homeopathic Nosodes are an alternative some guardians are using when choosing not to vaccinate. 

  • There is no evidence whatsoever that nosodes do anything but make money for people who sell them.

They (nosodes) do not produce titers against these diseases like a vaccination.

  • That's because they don't do anything.

Never vaccinate a sick or weakened animal.

  • Good advice.

Educate yourself.  Your veterinarian cannot make this decision for you, nor should they.  You are your companion’s guardian.  It is your responsibility to give them the best care you can by researching and carefully weighing your decisions about their healthcare.

  • That's true. However, you need to make sure you get good advice from all sources. You should consult with your vet and feel free to ask any questions. You should also scrutinize information available on the internet. Vaccination recommendations have changed in recent years, with longer intervals between boosters, and they certainly may change further as we learn more. I'm perfectly happy stretching out vaccine intervals based on good data. My pets don't get vaccinated every year. The key is to base decisions and changes on evidence so that we maintain the effectiveness of this critical disease-prevention tool.

The original source of the article was actually the Healthy Pet Journal, an online "journal" (site) published by a holistic/naturopathic veterinarian (who of course runs a clinic specializing in such services).  Always consider the source of what you're reading and the potential biases that come along with it.

Methicilin-resistant Staphylococcus schleiferi in pets

When it comes to methicillin-resistant staphylococci in pets, MRSA (methicillin-resistant S. aureus) gets most of the attention. That's fair since it's emerging as an important health problem, and can be transmitted between pets and people. Now another staph, MRSP (methicillin-resistant S. pseudintermedius) is getting more attention, and it's actually a more common cause of infections in dogs and cats compared to MRSA. There are also some other methicillin-resistant staph that get much less attention. One is methicillin-resistant S. scheliferi (MRSS).

There are actually two different subspecies of this bacterium, S. schleiferi subsp. coagulans and S. schleiferi subsp. schleiferi. Staphylococcus schlieferi subsp. coagulans is the coagulase-positive subspecies. (Coagulase testing is one of the main ways staph species are classified.) Sta[hylocccus schleiferi subsp. schleiferi is coagulase-negative. In general, coagulase-negative staph are considered to be minor concerns and rare causes of disease other than in sick, compromised individuals in hospitals. However, it looks like S. schleiferi subsp. schleiferi is an exception to that rule, as it is able to cause disease in otherwise healthy dogs and cats.

Both S. schleiferi subtypes predominantly cause skin and ear infections. As with other staph, methicillin-resistance is a concern and is increasing. Methicillin-resistant S. schleiferi (MRSS) rates appear to be increasing, which is a concern because methicillin-resistant staph infections are harder to treat due to their resistance to many antibiotics.

One factor that limits our knowledge of the role of MRSS (and really, S. schleiferi in general) in disease is the fact that many, if not most, diagnostic laboratories don't try to differentiate it from S. pseudintermedius because the two species are very similar. (Sometimes, labs don't even try to differentiate any of the coagulase positive staph, including S. aureus).

While MRSA in pets is a public health concern, there is probably much less to fear from MRSS. Staphylococcus schleiferi infections in people are quite rare and there is currently no indication that pets are an important source of human infection. However, given our limited knowledge of this bacterium, it's wise to take some degree of precaution around animals with MRSS infections, particularly basic measures such as avoiding direct and indirect contact with infected sites, and good handwashing habits. These are the same general recommendations for pets with MRSP, and more details about this are available on the Worms & Germs Resources page. 

Stray cat roundup in New Jersey

In response to recent problems with attacks by stray cats and concerns about rabies exposure, Point Pleasant Beach, New Jersey, is planning to round up all the stray cats they can catch. Cats will be monitored in rented trailers for 60 days, and any cats that do not have signs of rabies will be adopted out (after being vaccinated and spayed/neutered). It's perhaps overly optimistic that all cats will be adoptable, since not all strays (especially older cats) are going to be appropriate for household pets, but they will hopefully find good homes for many of these cats.

While this program could be beneficial in some ways, let's hope a lot of thought has been put into it. This type of mass roundup and confinement is quite likely going to result in high transmission of many infectious diseases that circulate in the stray cat population. Hopefully there are plans for proper initial health assessment of captured cats, isolation of cats showing signs of infectious disease, cohorting of different groups to reduce the risk of disease transmission and use of good general infection control practices. Without these, they are asking for major problems.  Unfortunately, infection control is often not considered in situations like this until a major disease outbreak is already underway.

The 60 day quarantine period may raise questions, but it's a reasonable approach. If they were doing a formal rabies quarantine, it would be six months. The maximum incubation period for rabies in cats is not known, but it can be very long in humans in rare instances. Realistically, 60 days is a pretty good quarantine period under these circumstances. You can't be 100% certain that an animal isn't incubating rabies after 60 days, but it becomes very unlikely and I wouldn't be concerned after 60 days. Sixty days is also a good amount of time to identify (and hopefully address) any other major health issues.

Another issue that needs to be considered is ongoing population control efforts such as continued catching and adopting of strays, catching and neutering strays, and educational efforts to encourage people to have their cats spayed or neutered and discourage them from feeding strays. A lot of time and money can be put into a big one-time effort, but this town might end up in exactly the same stray cat situation in a year or two if nothing else is done.

MRSA and vancomycin in dogs

Methicillin-resistant Staphylococcus aureus (MRSA) infections are an emerging problem in dogs and cats. They're a huge problem in human medicine, and the emergence of MRSA in pets can be directly traced to the spread of MRSA in people.

A big problem with MRSA infections is that they can be difficult to treat because they can be resistant to many antibiotics (not just methicillin). This complicates treatment, but it's important to remember that most MRSA infections are treatable.

An important concern with MRSA is that it may lead to unnecessary veterinary use of drugs that are critically important for treatment of life-threatening infection in humans. Vancomycin is an antibiotic that is occasionally used to treat MRSA infections in dogs, although I've never had to use it. I stumbled across a supposed "veterinary information website" today that stated vancomycin is the main treatment for MRSA in dogs. It quickly became clear the authors had no clue about the topic, because they kept calling MRSA a virus (always scrutinize the source of information, especially on the internet). Information like this doesn't help with prudent use of drugs like vancomycin.  It's important for pet owners and veterinarians alike to realize that these "big-gun" antibiotics (such as vancomycin) are rarely needed for MRSA infections in dogs and cats. There are almost always other, and usually better, options.

Vancomycin is also sometimes inappropriately used in animals, which can lead to worsening of infection.  For example, if vancomycin is mistakenly given orally, the drug is not absorbed from the intestinal tract and therefore has no chance of fighting infection elsewhere on the body.

In general, MRSA infections are quite treatable. Survival rates tend to be high and, with proper treatment, should be no lower for MRSA infections versus infections caused by susceptible strains of S. aureus. A comparison of MRSA versus susceptible S. aureus infections presented last year reported no difference in survival rates, with an overall survival rate of >80%. The key is diagnosing the infection early and getting started on the right treatment. That means getting cultures done earlier, rather than later.

While increasing antibiotic resistance may lead to more need for "big-gun" antibiotics in some cases, we need to act prudently and restrict their use to situations in which they are absolutely required. Use in animals needs to be very prudent to avoid contributing to antibiotic resistance in people. Inappropriate use in animals could lead to more calls to restrict veterinary access to various drugs, which could threaten treatment of other animals with other types of infections.

Don't confuse "big-gun" antibiotics with the best treatment.

More information about MRSA can be found on the Worms & Germs Resources page.

HIV/AIDS, kids and pets

The Centers for Disease Control and Prevention (CDC) has released updated Guidelines for the Prevention and Treatment of Opportunistic Infections Among HIV-exposed and HIV-infected Children. A small but still important part of this document involves recommendations for contact with animals. It's a nice, balanced document that acknowledges the risk but doesn't make unnecessarily restrictive recommendations.

Among the important recommendations regarding animals:

  • When getting a new pet, avoid dogs and cats less than 6 months of age or strays: These animals are at higher risk for shedding various infectious diseases and are more likely to have problems with biting and scratching.
  • Avoid contact with animals that have diarrhea.
  • Wash hands after handling pets.
  • Avoid contact with pet feces.
  • Avoid contact with reptiles, chicks and ducklings: These are very high risk for Salmonella.
  • Avoid contact with calves or lambs at farms or petting zoos: These animals are high risk for various infectious diseases such as Cryptosporidium and Salmonella.

These recommendations also largely apply to other high-risk groups, including people (of all ages) with compromised immune systems and young children (especially less than 5 years of age). A key point is normal contact with common household pest using basic hygiene practices is considered a low risk. Infection control isn't rocket science. It involves basic and practical measures that can reduce risks associated with animal contact.

Tea tree oil in dogs

Skin and soft tissue infections increasingly caused by highly drug-resistant bacteria, along with various concerns about antibiotic use, have led to a desire to find non-antibiotic approaches to treatment of these infections. Tea tree oil has some potent antibacterial properties when tested in the lab, and there are some studies indicating it might be effective for the treatment of certain infections. Some work that we've done in my lab shows promising activity of a few different essential oils against MRSP.  Some of these oil may be similarly useful treatments for certain infections. 

However, as I've stated before, we need to make sure that we adequately investigate safety of any new drug or therapy. All natural does not mean safer. If something kills bacteria, we need to make sure that it doesn't also harm an animal's cells and tissues.

Tea tree oil can cause damage to skin and soft tissue cells, but it's unclear whether this is really a problem during short courses of treatment. Nonetheless, in humans it has been recommended that tea tree oil not be used for treatment of burns because of concerns about tissue damage.(Faoagali et al, Burns 1997)

Another concern is toxicity from ingestion. This isn't usually a concern in adults, but there are a couple reports of children that became seriously ill (neurological abnormalities, progressive unresponsiveness... fortunately temporary) after ingestion of small volumes of tea tree oil. This leads me to have concerns about ingestion of the oil by dogs and cats if they lick areas where it has been applied, or eat bandages soaked in oil. They probably wouldn't ingest that much, but it's possible.

At this point, the jury is still out on the usefulness of tea tree oil. There are some potentially beneficial aspects and some safety issues that need to be clarified. In the interim, if you want to use tea tree oil:

  • Recognize it's not a proven therapy. Don't use it in place of conventional treatment recommended by your vet.
  • Keep it out of the reach of children and pets.
  • Be judicious about the amount you use, and make sure pets don't lick it off.
  • If the infected site seems to get worse after tea tree oil is used, stop applying it and see your veterinarian.

Internet ying/yang: Artemisinin use and safety

Yesterday, I received a bulk email ad advertising a book about Chinese herbal medicine in pets.One of the introductory statements said that Chinese medicine is "becoming more popular as people realize the powerful yet gentle ways of TCM healing." On the same day, I received a Morbidity and Mortality Weekly Reports article entitled "Hepatitis temporally associated with an herbal supplement containing artemisinin."

Also known as qinghaosu, artemisinins are a class of compounds (drugs) that are used for the treatment of malaria. They are the active constituents of the herb Artemisia annua (sweet wormwood). Herbal supplements containing these compounds are marketed for "general health maintenance" (whatever that means), treatment of parasites and treatment of cancer.

In the MMWR case report, the CDC was notified about a person who developed hepatitis while taking an herbal supplement containing artemisinin. The person was prescribed the supplement by a naturopathic practitioner who attributed the patient's chronic abdominal pain to a parasitic infection. Six weeks of treatment was prescribed but 1 week into treatment, signs of hepatitis developed. No other causes of hepatitis were identified, and it resolved after the person stopped taking the supplement. That doesn't prove the supplement was the cause, but it is suspicious.

The supplement was tested and it had the amount of artemisinin that the label claimed. Artemisinin is generally considered a safe treatment for malaria, however the prescribed dose was much higher than the dose that is conventionally used for malaria treatment. It's unclear whether the liver damage occurred because of the dose, interactions with other compounds in the supplement, or an unusual reaction in this patient.

It's important to remember that herbal therapies are drugs. The fact that they are still in their natural state does not necessarily mean they are safer. In fact, there can be increased risks because of inconsistency in potency, dose and the presence of other compounds. With conventional drugs, extensive testing is done before they are released, to reduce the risk of them making people sick. With alternative therapies, the opposite occurs. There is no mandated pre-release testing so harmful products are only identified after they make a lot of people or animals sick.

A drug is a drug, whether it comes in a pill, liquid or leaf form.

Comparing dog and cat bites

Animal bites are very common. Millions of people are bitten every year, and the resulting burden in terms of pain, infection and financial costs is astounding. Dog bites get the most press because they often cause significant trauma. Dogs have larger and stronger mouths, and can bite repeatedly and more aggressively in some attacks. Deaths attributed directly to pet bites pretty much exclusively involve dogs.

Cat bites are smaller and have less chance of causing significant injury to tissues, but they may be more severe in the long run. There's a scientific paper called "Cat bite infections: biological warfare amongst cats," which is a testament to the nasty populations of bacteria that live in cats' mouths. It's not just the presence of bacteria that's a problem (afterall, dogs' mouths are full of potentially nasty bacteria as well) - the nature of cat teeth and the resulting bite wounds is a major factor. Cat bites often result in small but deep puncture wounds. This pushes bacteria deep into the tissues, where they're harder to get rid of and which results in a much greater chance of causing an infection. Furthermore, cats tend to bite areas that are high risk for development of bad infections, especially hands, which have a complex and susceptible network of tendons, tendon sheaths, joints and nerves. Bites that appear to be minor can end up causing serious problems, often much worse that an initially more dramatic dog bite.

Really, you don't want to be bitten by either a dog or a cat (or an iguana, hamster, person or anything else). A large percentage of bites are avoidable, and knowing how to interact with animals and read signals of aggression or fear are critical. If you are bitten, prompt and proper care of bites is required to prevent serious, long-term complications.

More information on bites, including management of bites, is available on the Worms & Germs Resources page. The CDC has a podcast that includes information about bite-avoidance that can be accessed by clicking here.

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Attention Sears shoppers... Avoid rabid kittens!

State public health officials are trying to get the word out about a potential rabies exposure in Annapolis, Maryland.  A rabid kitten was discovered outside a Sears store at the Westfield Annapolis shopper center. The concern is that people may have handled the kitten and been exposed. It's a major concern with kittens because they can be hard to resist - a pathetic-looking/cute little kitten sitting around in a public place could easily be picked up by many people. Also, when rabies is found in a young kitten, there are often other rabid kittens from the same litter in the area. Rabid stray kittens have caused widespread exposure in the past, and this case may be no different.

Anyone who recently had contact with a stray kitten in the area in question should contact public health officials as soon as possible. Simply touching the kitten is not a rabies exposure risk, but anyone that has had any contact with a potentially rabid animal should talk to public health officials to determine whether there is any risk of infection and whether post-exposure treatment is required.

While kittens are hard to resist, avoid handling stray kittens. This is especially true if it's transient handling where you will never know what happened to the kitten afterwards (as opposed to someone adopting a kitten off the street - this is still risky from some standpoints, but at least you know if the kitten gets sick and you can make sure that it is tested for rabies or other other zoontic diseses, if need be).

Plague in a Colorado cat

A house cat in the Eagle, Colorado area has been diagnosed with pneumonic plague. Plague, caused by the bacterium Yersinia pestis, is a disease that still strikes fear into people. While we are long since removed from the period where the "black death" killed a large percentage of the population in Europe, plague still has a foothold is some regions of the world like the southwestern US. It is present in some wildlife (mainly rodents) and periodically infects people or domestic animals through transmission by infected fleas or direct contact.

Plague is periodically identified in cats - it's almost always outdoor cats that are affected since they have more interaction with wildlife and are at greater risk of flea infestation. Several forms of the disease can occur, including pneumonic, septicemic and bubonic plague. Pneumonic plague is a severe lung infection caused by the plague bacterium which is highly fatal.  This form is of particular concern because infected cats can spread the infection to people through aerosols produced by coughing and sneezing, or through contact with respiratory secretions. People caring for sick cats are at risk of developing plague (especially pneumonic plague, which is almost invariably fatal if untreated). Veterinary personnel are at particularly high risk. One study reported that 20% of people who contracted plague from cats worked in vet clinics. Of these, 25% of them died. 

If you live in an area where plague is present in wildlife, keep your cat indoors, avoid contact with wild rodents, keep wild rodents out of your house and make sure that you have a flea prevention program for you pets. If these things are done, the risk of disease transmission is very low.

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Humane society kids camp

I'm back from a week away with no internet access, so I have some catching up to do. One of the first things I stumbled across on my return was an article in the Guelph Tribune about a summer kids camp at the Guelph Humane Society. At the camp the kids get exposed to various aspects of animal care and welfare, and have field trips to sites like a Donkey Sanctuary and Butterfly Conservatory. Some parts of it sound quite good, but it's clear that the kids get to have a lot of contact with shelter animals, since playing with the animals is the "highlight of the camp," and as the camp director states "Who wouldn't want to hang out with cats and dogs all day?"

I have nothing against young kids having contact with pets (being the father of three young kids and the owner of multiple pets). Contact with animals is very rewarding for children, and a program to increase awareness about pets, animal care and the problems with overpopulation could be a great thing. However, I'm not sure that this is the best way. I only have a superficial idea of what happens at this camp based on the article, but I have a few different concerns.

Child safety

  • Any contact between people and pets carries some (albeit very low) risk of infection. Certain things increase the risk. One is young age. Kids are at increased risk of infection. The day camp had children between 5 and 13 years of age - the young end of this range certainly could be considered a high risk group.
  • Another issue is the increased likelihood that animals are shedding infectious agents. Shelter animals are definitely a high risk group, because of factors such as young age, stress, mixing of animals from various sources, illness, and under- (or lack of) vaccination and deworming.
  • The lack of good knowledge of temperament of these animals is another concern, as it's harder to predict whether an unfamiliar animal might be more likely to bite or scratch. I assume (hope) that the kids are only allowed to have contact with animals that have been assessed in some way, but it's difficult to know how an animal is going to react in certain situations.
  • Another consideration is the sometimes unpredictable nature of contact that kids have with animals. Young kids don't inherently know how to interact with strange animals. Even if they act very well around their own pets, they may act differently in a strange situation with animals that act differently, and not know how to detect or respond to signals that the animal is aggressive or afraid.  Education and supervision are important and should be a part of a program, but you can't instantly eliminate these risks.
  • The humane society environment can also be assumed to be pathogen-rich - there is a high likelihood that various surfaces (e.g. floors, counters) throughout the facility are contaminated with various bacteria, fungi and parasites.
  • Kids could also transfer infectious agents to the household, something that is of greatest concern if there are very young, elderly or immunocompromised individuals present.

Humane society safety

  • Humane societies are at constant risk of infectious diseases, including outbreaks. Outbreaks can cause major problems, including temporary closure, illness in staff or owners of newly adopted animals (e.g. ringworm), or mass euthanasia. Infection control measures can be highly variable in humane societies, and adding a group of kids to the mix certainly doesn't help. The more contact and movement in a facility, the greater the risk of disease transmission. Strict adherence to careful infection control protocols (which is not often the case, even at the best of times) is required. Good practices at the camp such as careful attention to hygiene, restricting contact with certain groups of animals, and very careful supervision could reduce the risk of disease transmission, but you can never eliminate the added risk that this type of program would bring.

Pet safety

  • Various infectious diseases could be transported home on the bodies of kids or their clothing. Some of these could pose a risk to any pets in the household. Risks are much greater if there are young, old, sick or inadequately vaccinated pets in the house.

I wonder whether the parents of these children were informed (in writing or otherwise) that their kids would be exposed to a increase risk of infectious diseases, bites and scratches, that they should take measures to reduce the risk of disease transmission when the child returns home, and what precautions are being taken at the camp.

MRSA testing and false advertising

I received a flyer from Zoologix, a company that offers various (typically unvalidated and unproven) PCR tests for animals. The flyer headline was "Pets can carry MRSA - but testing can help."

Testing in certain situations is useful, but this is almost always limited to diagnosis of animals with active infections (i.e. they're sick). PCR is not a good way to make such a diagnosis, because the test doesn't tell you anything about the bacterium's susceptibility to other antibiotics. Screening of pets just to determine whether or not they carry MRSA is rarely needed, and currently there is no evidence that PCR is a reasonable test for this.

There are no validated PCR tests for MRSA in animals. We looked at using a human test in horses and it failed miserably. There are validated tests for use in people, and they are quite good: they accurately identify MRSA and differentiate it from other methicillin-resistant staphylococci and from methicillin-susceptible S. aureus. That's critical, because you have to know what a positive test really means.

I called the company and asked what the test actually detects. They said it detects the mecA gene, the gene that confers methicillin-resistance to staphylococci such as S. aureus. However, this gene can be present in other staphylococci that can be found in many  healthy dogs and cats (10-30% in some studies). It does not actually detect MRSA and a large percentage of samples that give positive results will be false positives. The tests that are used in humans are specifically designed to look at two things in combination: whether S. aureus is present and whether it has the mecA gene (methicillin-resistance). This is the right approach because it excludes all those other false positives. Detecting mecA alone is completely useless. It's interesting that the flyer states "PCR testing is fast, effective and accurately differentiates MRSA from other bacteria - even other Staph strains." Based on what the company told me over the phone, with regard to the test they're advertising, that's a blatant lie.

This is an example of a combination of bad science and bad ethics. This company has no business marketing this test. It's false advertising, because the test isn't an MRSA test. Their justification for using it is similarly weak. Anyone thinking about using this test should run away quickly! The issues with this test (and others) should also be considered when deciding whether to use this company for any tests.

More (and accurate) information about MRSA can be found on the Worms & Germs Resources page.

Leave the rabid cat at home next time

A stray cat taken by someone to a family gathering in Delaware, USA, resulted in 17 people from 4 states undergoing rabies post-exposure treatment. The kitten was found by the side of the road, taken to the gathering (it's unclear whether it was found on the way there or earlier), and when it became ill after the gathering, it was diagnosed with rabies. This is just one example of the potential for widespread exposure of people handling stray (or recently stray) animals at events like reunions, flea markets and sports tournaments. Because these animals (especially cute little ones like kittens) often get handled by a lot of people, a lot of people can be exposed to rabies if the animals are carrying the virus. These situations create major problems for public health personnel, because it's difficult to identify all the individuals who were potentially exposed when they are dispersed across the country.

While generally uncommon, this type of scenario happens a few times a year.

  • Don't bring stray, or recently adopted, animals to public events.
  • Ensure that your animals are properly vaccinated against rabies. Animals that have not been properly vaccinated should not be taken to public events.
  • Don't handle stray animals.
  • If an animal that you have recently adopted gets sick, make sure rabies is considered and, if necessary, make sure the animal gets tested.

Antibiotic use compliance

In an interview with the San Francisco Chronicle, veterinary dermatologist Dr. George Doering makes a pretty obvious but very important comment that is worth repeating:

"The biggest problem we have in almost all the fields of veterinary medicine is compliance. You say to a client, "This dog needs to take this antibiotic twice a day." Well, the reality is we might be lucky if they get it once a day. ...They don't want to accept the seriousness of the problem."

This very true and very important. Compliance with recommended antibiotic therapy is probably a major factor in treatment failure, recurrent infection and antibiotic resistance. Antibiotic dosing regimens are specifically designed to ensure that the right concentration of drug is present in the body for the appropriate time. Missing doses, skipping days, not making sure the animal actually ingests the drug, and other problems that result in the pet not getting what is was supposed to get are very important.

It's easy to understand why this happens, because administering antibiotics (particularly to some difficult-to-pill dogs and cats who can smell the medication when it comes in the house!) can be a hassle. Because of this (and the very natural human tendency to take the easy way out), it's really important for people to understand the concerns about inadequate antibiotic administration and what they need to do.

  • Follow the entire treatment course. You should have no antibiotic left at the end of the recommended treatment time.
  • Make sure your pet actually swallows the antibiotic. If you add pills to food, make sure you check to see that the pill isn't left behind. It's amazing how animals can eat a big bowl of food and leave behind a little pill. The picture shows how my dog Meg can, in the process of inhaling her food at an incredible rate, leave behind a tiny ephedrine pill.
  • If your pet will not eat the drug voluntarily, talk to your vet about other ways to administer it, such as compounded in chewable treats. Depending on you and your pet, opening your pet's mouth and placing the pill at the back of the tongue may be an option. Talk to your vet about this first and make sure you wash your hands after. If you think there is a risk you might be bitten, if you are at high-risk for infection because you are immunocompromised, elderly or pregnant, don't try to "pill" an animal in this manner.
  • If you still can't get the drug into your pet, talk to your vet right away.  If you wait a couple of days or a week or more to tell your vet, your pet may be even sicker by then. There may be other options to oral drugs such as injectable antibiotics. This might end up being more expensive or difficult (e.g. you may have to take your pet to the vet every day for its medication), but it will be better for your pet and may even save you money in the long run by ensuring the infection is properly and completely treated the first time.
  • Never stop treatment because your pet looks better. Often, signs of infection get better before the bacterium is completely eliminated. Stopping too soon allows the bacterium to regrow, potentially as a more resistant form.
  • If you are supposed to take your pet to the vet for a recheck at the end of treatment, then do so. Sometimes longer courses of antibiotics may be needed, and it's much better to continue the current treatment course than to have to start again a couple weeks down the road when the infection has returned (sometimes with a vengeance).
  • If in doubt about anything, call your veterinarian.  He or she is there to help, and wants your pet to get the best treatment possible.

Tularemia in cats and dogs in Sioux Falls

Tularemia has been diagnosed in five dogs and cats in Sioux Falls, South Dakota. At least one of the pets has died. Tularemia, sometimes referred to as "rabbit fever" is caused by the bacterium Francisella tularensis. Infections occur throughout much of the Northern Hemisphere but are much more common in certain regions, such as the central US. This bacterium has received a lot more attention over the past decade because of its potential use as a bioterrorism agent, but infections have been occurring in people and pets for a long time. In North America, the cottontail rabbit, wild hares and some rodents are the main reservoirs. People and other animals get infected through close contact with infected animals (e.g. rabbit hunting) or through bites from blood-feeding insects. 

There was no mention of human cases in the recent report from South Dakota. One of the implications of identifying this disease in pets is that whatever infected the pet could also be a risk for people. If the pets were infected by contact with wild animals, people with similar contact with wild animals could also be exposed. If there is no chance the animals had contact with infected wildlife, then insect-transmission is most likely, and the same could happen to human members of the household (or elsewhere in the area). Therefore, diagnosis of tularemia in a person or pet should put both veterinarians and physicians on the lookout for further cases in all species.

Transmission of tularemia from infected pets to humans is also a concern. This has been reported in numerous instances, most often with cats. There are published reports of transmission from dogs to humans, but these are less convincing than the numerous cat-to-human reports. There's also a report of tularemia transmission from a hamster to a child. The overall risk of transmission is probably low, but tularemia can be spread from pets to people by scratches, bites, and perhaps regular close contact.

You can reduce the risk of your pet being exposed to tularemia by:

  • Keeping pets indoors as much as possible. Cats should stay indoors. Dogs should not have uncontrolled outdoor access.
  • Dogs should not be allowed to hunt rabbits in areas where tularemia is endemic.
  • Animals that venture outside should be checked regularly for ticks and a preventive medicine program for ticks should be in place.
  • Routine measures to reduce bites and scratches from dogs and cats should be taken.

Cats and Q-fever

I was reading an interesting old paper the other day about Q-fever in cats. Q-fever is a zoonotic disease caused by Coxiella burnetii. It is most commonly associated with contact with sheep, cattle and to a lesser extent goats, around the time they give birth. This bacterium is highly infectious - it only takes a small number of bacteria to cause disease. (That's one of the reasons it's classified as an important bioterrorism agent).

While most of the focus in on ruminants, there have also been many reports of Q-fever associated with cats, also mainly through contact with these animals around the time they give birth.  Cats may be the most important Q-fever reservoir in urban areas.

The study I was reading, a 1988 article from the journal Chest, describes a Q-fever outbreak in a town in Nova Scotia. Thirty-three people were infected in the town of Baddeck (population 900, meaning 2.8% of the population was affected). Forty-two percent of infected individuals lived in four side-by-side buildings. Investigation revealed that most infected people had contact with a cat that have given birth to stillborn kittens (stillbirths are common in cats infected with Coxiella). The cat lived in one of the four buildings and regularly visited neighbouring buildings.

This is just one of many reports of Q-fever associated with cats. Almost all involve direct contact or being in the vicinity of cats around the time of birth. Since this bacterium is so infectious, and can even be spread through the air through aerosols (e.g.dust, tiny droplets of fluid), direct contact (e.g actually touching the cat) is not required for infection to occur.

That being said, cat-associated Q-fever is probably still pretty uncommon, but Q-fever can be a very serious disease. Since transmission mostly involves cats at the time of birthing, a few basic measures should be able to greatly reduce the risks:

  • Avoid contact with cats that are giving birth or who have done so recently.
  • Avoid contact with newborn kittens and areas contaminated during the birthing process.
  • If your cat is going to give birth, try to have it do so in a well-ventilated area away from areas where people spend time and away from areas where food is prepared.
  • If contact with the mother cat, kittens or areas/items contamination with birth fluids is likely to occur, gloves should be worn. Hands should be washed after gloves are removed.
  • If a cat gives birth inside, the area should be thoroughly cleaned and disinfected afterwards. Gloves should be worn for this.
  • The risks are probably higher with stray cats (who are more likely to be infected), so extra care should be taken to avoid contact with stray cats around the time of birth.

More information about Q-fever can be found in the Worms & Germs archives.

Kids exposed to rabies from stray kitten

Two kids and one adult are undergoing post-exposure treatment for rabies after having contact with an infected kitten. One child saw the stray animal and went to give it some food, and he was bitten in the process. The kitten then proceeded to bite the boy's mother and another child in the neighbourhood. Fortunately, the kitten was taken to animal control and was identified as a rabies suspect. It was euthanized and testing of the brain confirmed it had rabies. Accordingly, the three bitten people are now undergoing post-exposure treatment. Animal control is handing out flyers in the neighbourhood to warn others, as there may be more rabid animals in the area. One particular concern with young kittens is that sometimes multiple animals from the litter are infected, so there may be more cute but deadly kittens in the area.

  • Avoid contact with stray animals. That's the best way to avoid getting bitten by one.
  • If you are bitten by a stray animal, the animal must be caught and quarantined. If you don't know the rabies status of an animal that has bitten you, you have to consider it rabid and get treated. If you are bitten by a stray or wild animal, call animal control to catch it. If you can safely contain it (e.g. lock it in a garage) without putting other people at risk, do so and then wait for animal control to capture the animal.
  • Vaccinate your pets.

Rabies quarantine

There are two situations when animals may be quarantined because of rabies concerns:

  1. After biting a person.
  2. After potentially being exposed to a rabid animal.

The time frame for quarantine in these two situations is quite different because of what the quarantine is meant to accomplish.

Animals that have bitten someone are quarantined for 10 days under observation to see if they develop signs of rabies. Most animals that bite do not have rabies, and this is the easiest way of determining whether the animal could have potentially transmitted rabies by way of the bite. If an animal was rabid and infectious at the time of biting, it would die from the disease within 10 days. Animals can only transmit rabies virus after it has reached the brain and started to spread outwards via nerves - it gets into saliva by working its way down nerves from the brain to the salivary glands. Once an animal gets to that stage of disease, they die quickly. So, if the animal is still alive after 10 days, it was not rabid at the time of the bite. Quarantine is important so that it can be clearly proven one way or the other whether the animal was rabid. If the biting animal was not quarantined and ran away, the recommendation would be to err on the side of caution and treat anyone bitten as if they'd been exposed... but we want to avoid that if at all possible.

The second type of quarantine (for a potentially exposed animal) is based on less solid evidence. The idea in these cases is to keep the potentially exposed animal isolated while waiting to see if it develops signs of rabies, because there is no other reliable test for rabies in a live animal. For example, if an unvaccinated dog gets into a fight with a rabid raccoon, it would be considered potentially exposed. It would be quarantined (or immediately euthanized... the other option) and monitored to see if it develops signs of rabies. The length of quarantine for non-vaccinated dogs is usually 6 months, but this may vary by region. This helps reduce further rabies transmission by ensuring that a dog that develops rabies during the quarantine period is not roaming at large and able to infect people or other animals. One weakness of this approach is the incubation period of rabies, which can be very long. There is not a lot of objective research on which to base the 6 month time frame (unlike the 10 day quarantine described above). After 6 months, it's very unlikely the dog will develop rabies, but we can never say it's 100% because of the rare cases of rabies in humans with extremely long incubation periods. In reality, it's likely that the vast majority of animals that are exposed will develop rabies before 6 months, so it's a reasonable time frame. Would it be better to use 4 or 8 months, or something else? Possibly, we just don't know.

The easiest ways to avoid hassles associated with rabies quarantine are:

  • Prevent bites. If your pet is trained and observed properly, it's unlikely to bite anyone, so the 10-day post-bite quarantine shouldn't be an issue.
  • Vaccinate your pet. Properly vaccinated pets are not subject to the same long, strict quarantine (although a shorter period of isolation (often at home) is usually still required).


"The other TB" Mycobacterium bovis

Tuberculosis (TB) is an incredibly important disease caused by Mycobacterium tuberculosis. It's a huge problem internationally, and the problem is getting worse in many areas. Another cause of "tubercular" (or tuberculosis-like) disease is Mycobacterium bovis, a related microorganism whose main natural reservoir is cattle.

Mycobacterium bovis is cause of bovine TB. It can also infect people (usually through drinking or eating unpasteurized dairy products) and pets. Pets can be exposed by a few different routes, including eating contaminated dairy products, eating infected animals (e.g. snacking on carcasses of wildlife like deer that have died of the disease), and perhaps from direct exposure to wildlife carrying the organism. Mycobacterium bovis is an important problem in some areas, typically because of its presence in a wildlife reservoir like deer or the European badger (a major problem in the UK).

Mycobacterium bovis can cause serious disease in pets. It often causes non-specific signs that makes it hard to diagnose until disease is very advanced (and unfortunately likely beyond the point of successful treatment). Some groups recommend prompt euthanasia of infected pets without considering treatment because of the potential for infection of people. The risk of pet-human transmission is completely unclear, but it's such an important disease that some people think any risk is unnecessary and unjustifiable. So, the key is avoiding infection in the first place (for both people and pets). This is of particular concern in regions where M. bovis is present in wildlife and cattle. In areas where it is not known to be present, there should be little to worry about.

Here are some simple steps that can help you reduce the risk of your pet becoming exposed to M. bovis:

  • Keep cats indoors.
  • Don't allow dogs to roam free outdoors.
  • Don't allow animals to have access to unpasteurized dairy products or dead animals.

Pretty basic, isn't it?

Meningitis in a baby linked to pet cat

A paper in the Journal of Clinical Microbiology back in 2000 described a case of Pasteurella multocida meningitis in a one-month-old baby that was linked to a pet cat. Pasteurella multocida is a bacterium that can be commonly found in the mouth of healthy dogs and cats - 90% or more of healthy cats may have it in their mouth. The organism can cause infection in humans.  These cases are usually associated with close contact with animals, such as bites, scratches and licking wounds. In this case, there was reportedly little contact between the baby and the cat, yet the same P. multocida strain was found in both. The cat was healthy and the bacterium was found in its mouth. There was no clear route of transmission (like a bite or a scratch), however unidentified contact with the cat or (more likely) indirect transmission of the bacterium from the cat to the baby by another person are possible.

This is a good example of the unpredictable nature of zoonotic infections. There was no reported underlying disease that made this baby more susceptible to infection. It's just that being very young (or very old, or immunocompromised) means you're more likely to develop infections from the myriad bacteria that are present all around us. While this infection might not have been preventable, we need to think about good routine precautions involving contact of pets with babies.

  • Keep them apart (but not completely). Pets should not be allowed to lick or have other close contact with a young baby. That being said, household pets need to be around the baby to learn to interact with the child safely, and recognize the baby as a member of the family, but supervision is needed and direct contact should be avoided.
  • Good hygiene should be used around pets and babies (individually and together). Hands are the main source of disease transmission and regular hand washing is a great infection control tool.

Baylisascaris (raccoon roundworm) in cats











Parasite exposure from pets









Reference: Overgaauw et al, Veterinary Parasitology, 2009.

Preventing infections in the home




Canadian parasite treatment guidelines for pets



Clostridium difficile in the household environment

