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Canine Influenza Virus

Canine Influenza Virus

Canine influenza virus (CIV) is a viral respiratory infection. There have been two identified strains of the virus in the US: H3N8 and H3N2. These viruses are considered to be endemic in the United States and there have been cases of both strains in Oregon.


Canine influenza is an airborne disease, much like kennel cough (Bordetella bronchiseptica). The highly contagious virus can travel in droplets from a cough or sneeze and can be transmitted by contact with contaminated objects (for instance, a chew toy or clothing).

If your dog stays at home and rarely contacts other dogs, its risk of contracting the virus is likely low. However, dogs in close contact with potentially infected dogs in places such as kennels, groomers, day care facilities, shelters and rescues are at increased risk of infection. Dogs with pre-existing heart disease or lung disease, some senior dogs, and brachycephalic breeds may also be at risk.

If your dog is coughing, it should not go to public places where it could contact other dogs until your veterinarian agrees it's safe for your dog to go out.



The most common clinical signs are coughing, loss of appetite, lethargy, fever, sneezing, and discharge from the eyes and/or nose. These symptoms can be very similar to kennel cough or any other respiratory infection.

Dogs can become ill within 24 hours of exposure. Some dogs don’t show symptoms, but are able to infect other dogs for weeks. Most dogs diagnosed with canine influenza experience a mild form of the disease. In up to 20% of affected dogs, the illness can become very serious due to the possibility of a secondary infection, such as pneumonia.

Call your veterinarian if your dog develops a cough, especially if it has already received the Bordetella vaccine. If your dog is coughing, or shows the above symptoms, do not take it out to locations where it may contact/infect other dogs. Early intervention is key to limiting community outbreaks.

Be sure to tell your veterinarian if your dog has been boarded, sent to the groomer or involved in any social activities (dog park, day care, etc.) within the last month.

Remember, coughing can be indicative of a variety of significant diseases or conditions. Your veterinarian is best qualified to diagnose your dog.


Similar to influenza treatment for people, canine patients need rest, hydration, and treatment for their symptoms. This could include cough suppressants and appetite stimulants. They should also be monitored for secondary infections that may require antibiotics. In order to decrease the chance of spreading the virus, it’s best not to hospitalize dogs with influenza if they can be treated safely at home.

CIV is rarely fatal but can cause complications in dogs that are very young, very old, have weakened immune systems or other health issues.


After handling a sick dog, wash your hands before touching your dog. Avoid contact with dogs that appear sick.

Vaccines are available for both strains. Two doses are needed. If your dog goes to day care or if you plan to board your dog, CIV vaccination may be recommended or required. The Bordetella vaccine does not protect dogs against canine influenza.

Discuss your dog's specific risk factors with your veterinarian to determine whether vaccination against canine influenza is appropriate for your pet.

Two strains: H3N2 & H3N8


In 2019, a handful of H3N2 cases were diagnosed in rescue animals brought into Oregon from other states/countries.

In addition to dogs, cats have been confirmed to have also been infected with the H3N2 virus; however, the risk to most cats living outside of shelters is considered low, with the highest risk factor being infection in a household dog, so prevention of illness in dogs is key to the health of other animals in the household. There is some evidence that guinea pigs and ferrets can become infected.


According to the Centers for Disease Control, the first evidence of H3N8 canine influenza in companion dogs was documented in spring 2005. It is believed to have jumped species from horses and was first identified in an outbreak of respiratory illness in racing dogs in Florida in 2004. H3N8 does not affect cats. A few cases of this strain were reported in Oregon in 2013.

Updated: February 1, 2020

Sources include: AVMA, Oregon Public Health Veterinarian's office, CDC