By Ellen Fannon, DVM


The two most common causes of chronic itching in dogs are external parasites, such as fleas, and allergies.  Some people are surprised to find that animals can have allergies just like people, but unlike the hay fever symptoms people experience, allergies in pets are a common cause of chronic skin and ear problems.  Animals with allergies often scratch, lick their feet, rub their face or belly on the ground, and chew at themselves.

Flea allergy dermatitis is the most common skin disease in dogs.  For these animals, diligent, year-round flea control is the essential key to keeping them comfortable.  I wish I had a nickel for every client who has told me he never sees fleas on his dog. These people are in “flea-nial.” Just because you don’t see fleas doesn’t mean your pet doesn’t have a flea allergy.  For a flea-hypersensitive dog, just one flea bite can cause a reaction, and the adult flea may have taken its’ blood meal and be long gone.  Scratching, chewing, and hair loss over the lower part of the body is often an indicator of a flea allergy.  Flea allergies may lead to secondary conditions, such as bacterial and yeast infections due to skin irritation.

Fortunately, there are many newer, efficient products available to help fight the battle of the flea. I personally like the oral products, such as once-a-month Nexgard or Comfortis, and once-every-three months Bravecto.  Trifexis is another oral flea control product in conjunction with monthly heartworm prevention.  I also like the Seresto collar, which lasts seven to eight months.  There are many other good products on the market, and newer ones are coming out all the time.  I would recommend staying away from some of the over-the-counter products, which are often not as effective, and in some cases have caused toxicity in pets.  Also beware of internet pharmacies unless they carry the VIPPS®(Verified Internet Pharmacy Practice Sites) Seal.  You can visit the VIPPS® website to find legitimate pharmacies.

Remember the environment (house and yard) must also be treated for fleas to ensure optimal flea control. Flea eggs can survive for long periods of time under harsh conditions, so it is possible to have a flea infestation in an area where there have been no pets for several months.  I prefer to use a professional exterminator for the environment, as they have access to the latest and safest treatments and their work is guaranteed.  However, there are also products available for do-it-yourself pest control.

If you need further reason to practice excellent flea control on your pets, fleas can carry diseases infectious to humans, such as Bartonella, the causative agent of Cat scratch disease. Bartonella has also been associated with inflammation of the heart muscle and joints, and can be confused with other immune-mediated and chronic inflammatory diseases.  Fleas can also carry diseases such as plague and typhus.

The second most common cause of itching in dogs is allergies.  Dogs can be allergic to the same things as people, such as grass, pollen, mold, weeds, trees, dust, mites, and food.  Allergies may be seasonal or year-round.  Some people find that their dog never had allergies until they moved to a different part of the country, or even to a new home in the same area.  Secondary problems such as bacterial and yeast ​infections, as well as chronic ear infections are common with allergies, and unlikely to clear up unless the allergy is controlled.

Fortunately there are several effective ways to manage allergies.  Allergy testing can be performed in animals, just as in humans.  If there is a dermatologist in your area, intradermal skin testing is the gold standard for identifying environmental allergens.  If not, blood samples can be sent to a lab to look for antibodies against allergens.  After identifying the specific substances to which the dog is allergic, allergy shots can be given in order to desensitize the animal to those offending substances. Recently, an oral allergy serum has become available, making it much easier for pet owners.  Desensitizing a dog to allergies may take several months, and there is a potential to make the pet worse while undergoing treatment, so careful monitoring and record keeping is important.  The initial expense can be high, but considering the amount of money clients spend on an itching pet over its lifetime, the cost is often worth it.

Two newer products which have worked well in allergic dogs are Apoquel tablets and Cytopoint injections.  These both work to block the inflammatory response causing itching.  Apoquel is generally given daily, whereas Cytopoint is given every 4-8 weeks.  The good news is that these products do not have the side effects associated with steroids.  The bad news is they can be expensive.  However, to a lot of owners with itchy dogs the cost is more than worth it to give their pet relief.  Steroids are very effective in controlling itching and they are inexpensive, but should not be used for long term control of allergies.  Side effects of steroids include increased drinking, urinating, and appetite, weight gain, and increased risk of infections.

Antihistamines, such as Benadryl can often help control mild itching, but may not be strong enough if the pet is thoroughly miserable.  Bathing with medicated shampoo, antihistamine or cortisone shampoo, or oatmeal shampoo can often provide temporary relief from itching.  It is best to check with your veterinarian as to which type of shampoo is best for your pet’s condition. I often find that people spend a lot of money at pet stores on shampoos which aren’t right for what the animal needs.  Other topicals to help control itching are available, such as conditioners, mousses, and sprays.  Omega-3 fatty acids are also helpful for a number of skin problems.

Food allergies are much less common than environmental allergies, making up only about 4% of skin allergies.  Because food allergies are diagnosed and managed differently, I will address that issue in the next column.


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