Canine Influenza H3N2 FAQ

The canine influenza outbreak that began in the Chicago area in March of 2015 and spread to other areas across the country over the next year is caused by a different strain of the virus than was earlier assumed, according to laboratory scientists at Cornell University and the University of Wisconsin. Researchers at Cornell say results from additional testing indicate that the outbreak is being caused by a virus closely related to Asian strains of influenza A H3N2 viruses, currently in wide circulation in southern Chinese and South Korean dog populations since being identified in 2006. The following is a list of Frequently Asked Questions about H3N2. The answers are based on what we know to date.

Does H3N2 pose a risk to humans? Is there any chance it will jump to cats or other small pets?

At this time there are no known cases of this influenza virus infecting humans, though authorities such as the CDC are monitoring the situation closely.

This subtype of the virus was found to be the cause of disease in a number of cats in South Korea in 2010. A single shelter-associated outbreak in cats  was identified in 2016 in the Chicago area. These have been no additional reports of H3N2 in cats since this report. There is no vaccine available for cats.

Will the vaccine developed for H3N8 protect against H3N2?

Although both are H3 viruses, H3N2 is antigenically different from the H3N8 virus strain. As a consequence, a novel vaccine containing the H3N2 virus has been created and released for use. Vaccines are currently available as independent formulations or as a combination including both H3N2 and H3N8 strains.

How can owners protect their pets?

Owners should check with their veterinarian to find out if the influenza virus has been a problem in their area.  If the dog is deemed to be at increased risk, it may be prudent to keep the dog out of situations where contact with other dogs can occur. Care should be taken when handling a dog that has respiratory disease. Contaminated objects such as leashes and toys can spread the virus from one dog to another, as can people who have touched an infected dog.

What kinds of dogs are most at risk for H3N2?

As with H3N8, dogs at most risk are those that have contact with other dogs, particularly those that are having symptoms of a respiratory infection. Situations that pose risk include boarding kennels, grooming salons, canine daycare, dog parks, animal shelters, and any other locations where dogs can interact. As with other infectious diseases, extra precautions may be necessary with puppies, elderly dogs, and dogs that are immunocompromised for any reason.

Especially severe disease has been seen in some groups of greyhounds.

What are the symptoms?

The symptoms are respiratory in nature and can vary from dog to dog. Some have no symptoms while others become severely ill. Most dogs are only mildly affected with a fever, runny nose, and a cough. Others can suffer from life-threatening pneumonia that requires veterinary care.