Contagious Canine Diseases

By Deborah Lundin

Dogs spread diseases between each other through direct and indirect contact. In addition to spreading diseases among dogs, some canine diseases are zoonotic -- able to spread to other species, such as humans. Knowing these diseases and the symptoms allows you to isolate a sick dog from others and acclimates you to using appropriate precautionary measures so you don’t contract an illness.

Canine Distemper

Canine distemper is a highly contagious viral disease. A vaccination exists, but unvaccinated adults and puppies are susceptible. The virus spreads through the air and enters the respiratory system. Initial symptoms include high fever, red and watery eyes, nasal discharge, lethargy, coughing, loss of appetite, vomiting and diarrhea. As the disease progresses, it attacks the nervous system, resulting in seizures and paralysis. Also known as hard pad disease, distemper causes hardening of the foot pads. There is no cure for distemper, and treatment focuses on reducing symptoms and maintaining hydration.

Canine Infectious Hepatitis

Canine infectious hepatitis, caused by canine adenovirus type-1, spreads through direct contact with infected urine. When a dog sniffs an area with infected urine, the virus enters through the nose and mouth. A vaccine is available, but puppies and unvaccinated dogs are at risk. Symptoms include nausea, vomiting, loss of appetite, jaundice, high fever, swollen lymph nodes, low white blood cell count, tonsillitis, palm gums and tongue and light-colored stools. Treatment focuses on symptoms and includes maintaining hydration and blood sugar.

Canine Infectious Respiratory Disease Complex

Canine infectious respiratory disease complex, also known as kennel cough or infectious tracheobronchitis, is a highly contagious upper respiratory condition caused by a variety of viral and bacterial agents. Viral examples include parainfluenza virus, adenovirus, corona virus and herpes virus. Bacterial causes include Bordetella bronchiseptica, Mycoplasma spp. and Streptococcus equi. Symptoms include coughing, nasal discharge, sneezing and watery eyes. Often, pneumonia can develop. Standard vaccinations protect against infection by the parainfluenza virus, adenovirus, influenza virus and bordetella. Treatment depends on the underlying infectious agent.


Parvovirus, or parvo, is a highly contagious disease that spreads through direct contact with infected dogs or feces. Vaccines are available, though unvaccinated puppies and dogs are susceptible to infection. Symptoms include lethargy, severe and bloody diarrhea, vomiting, loss of appetite, severe weight loss and fever. With no cure available, treatment focuses on the symptoms and maintaining hydration. The survival rate for dogs, according to PetMD, is about 70 percent.

Zoonotic Diseases

When you think of a disease that can pass from dogs to humans, dog bites and rabies may come to mind. While this is a viral condition, many bacterial conditions spread between dogs and humans. These include Leptospirosis, Salmonella and E. coli. Leptospirosis, caused by Leptospira interrogans, passes through skin contact. Symptoms include fever, sore and stiff muscles, increased thirst and urination, vomiting, diarrhea, difficulty breathing and nasal discharge. Salmonella and E. coli both cause gastrointestinal symptoms. Always wash your hands before and after coming into contact to avoid catching anything.

By Deborah Lundin


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