Canine Influenza Outbreak

You may have heard about the recent outbreak of a new type of dog flu affecting pets across the country. This highly contagious and, for some dogs, potentially serious respiratory infection is called canine influenza virus H3N2, or CIV H3N2 for short. There are actually two strains of dog flu that can cause serious disease or even death: H3N8 and H3N2. H3N8 and H3N2 are the strains causing canine influenza in our pets. Chances are, if your dog is exposed to CIV H3N2 or CIV H3N8, he or she may become infected. Dogs that are frequently in contact with other dogs are at the highest risk of infection with both strains of CIV. This includes dogs that are boarded, enrolled in daycare, or often visit the local dog park. Dogs of all ages and breeds are at risk for this highly contagious disease.

The good news is that we have vaccines available to help control disease associated with CIV H3N2 and H3N8. Dogs need to be vaccinated for both strains in order to be fully protected because both strains have been diagnosed in over 38 states to date.

What is Canine Influenza?

Canine influenza, or dog flu, is a highly contagious respiratory infection of dogs that is caused by an influenza A virus. In the United States, canine influenza has been caused by two influenza strains, H3N8 and H3N2. H3N8, first reported in the United States in 2004, is closely related to the virus that causes equine influenza. In 2015, an outbreak that started in Chicago was caused by a separate canine influenza stemming from a separate strain of canine influenza virus, H3N2. The strain causing the 2015 outbreak was almost genetically identical to an H3N2 strain previously reported only in Asia – specifically, Korea, China and Thailand. In Asia, the H3N2 strain is believed to have resulted from the direct transfer of an avian influenza virus – possibly from among viruses circulating in live bird markets – to dogs. We do not yet know how it got to the United States.

Is There a Vaccine for Canine Influenza?

The first vaccine for canine influenza virus H3N8 was approved in 2009, and there are several H3N8 canine influenza vaccines available. In November 2015, the U.S. Department of Agriculture (USDA) granted Zoetis a conditional license to supply veterinarians with Canine Influenza Vaccine, H3N2. PetVet now carries vaccines for both strains in the package. Dog owners should consult the veterinarian to determine whether vaccination is needed.

NOTE: Vaccination with DA2PP or the “kennel cough” vaccine for Bordetella bronchiseptica does not provide any immunity to canine influenza.

How Widespread is The Disease?

Canine influenza has occurred in more than 36 states nationwide. The first recognized outbreak of canine influenza virus in the world is believed to have occurred in racing greyhounds in January 2004 at a track in Florida from the H3N8 strain. From June to August of 2004, outbreaks of respiratory disease were reported at 14 tracks in 6 states (Alabama, Arkansas, Florida, Kansas, Texas, and West Virginia). Between January and May of 2005, outbreaks occurred at 20 tracks in 11 states (Arizona, Arkansas, Colorado, Florida, Iowa, Kansas, Massachusetts, Rhode Island, Texas, West Virginia, and Wisconsin). The canine influenza virus has been reported in at least 36 states and Washington, DC. The H3N2 strain of canine influenza virus had been reported in Korea, China and Thailand, but had not been detected outside of those countries until 2015. In April 2015, an outbreak that started in Chicago was caused by an H3N2 strain that was genetically almost identical to the strain in Asia. In the period from March 2, 2015, to September 31, 2015, CIV H3N2 was found in 25 states.