Canine Influenza

Canine Influenza is a disease caused by a virus that infects the respiratory tract of dogs. The disease is accompanied by normal respiratory disease signs such as sneezing, coughing, ocular/nasal discharge, wheezing, fever, and lethargy.

Two different strains of canine influenza (CI) have been found in the United States since 2004, H3N8 and H3N2. The current strain of CI that has been circulating throughout the Midwest is an H3N2 strain that started with an outbreak in the Chicago area. Since this is a relatively new virus, virtually all dogs are naïve (have no immunity to it) and will become infected if exposed. 80% of these dogs will develop some combination of signs of the disease, and 20% will show no signs, but may shed the virus.

Most dogs do not become extremely ill when infected, although some may become susceptible to pneumonia or other secondary bacterial infections, such as Bordatella bronchiseptica (Kennel Cough). For this reason, it is important to booster Bordatella vaccines if the CI virus is found near your area.

There are vaccines for Canine Influenza type H3N8, but there is little evidence to support any cross protection with the H3N2 virus, which is why most veterinary clinics don’t carry the vaccine.

The virus is spread via aerosol secretions (more pronounced in enclosed settings) and on contaminated objects (food bowls, clothing, toys, leashes, beds, etc.). The virus can remain viable (alive and able to infect) on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours. Dogs will be most contagious during the first 24 hours after being infected. It is important to note that they will not be exhibiting any signs during this time. They can remain contagious up to 10 days following infection.

The virus is easily killed by disinfectants such as bleach. Thoroughly cleaning and disinfecting all objects used around the pet is essential to preventing viral spread. Dog owners whose dogs are coughing or exhibiting other signs of respiratory disease should not participate in activities or bring their dogs to facilities where other dogs can be exposed to the virus. Outbreaks are more commonly seen in situations where groups of susceptible dogs are in close contact, such as shelters, kennels, dog day care facilities, and boarding facilities.