Baker Institute for Animal Health


H3N2 influenza: how to protect your dog

UPDATE: Please be aware there have been several updates regarding H3N2 since this article has been written, including the development of a vaccine against the virus. Get the latest information.

H3N8 canine influenza vaccines are unlikely to work against the H3N2 strain that has infected hundreds of dogs in the Midwest.

An outbreak of canine influenza in the Chicago, Illinois area that began earlier this year has since spread to neighboring states, and the Baker Institute is working to understand the outbreak and share information with owners, veterinarians and breeders. Director Dr. Colin Parrish describes some of what is known about the virus and how to prevent infection in a recent press announcement, reproduced below.

Dr. Parrish's lab is studying blood samples from dogs sickened in Midwest outbreak to pinpoint the identity of the virus strain responsible and identify ways to treat or prevent infection. Earlier this month, scientists at Cornell's Animal Health Diagnostic Laboratory identified the virus responsible for the outbreak as a strain of H3N2 influenza that had previously only been seen in Korea, China, and Thailand. Stay tuned to our website for more on the virus and the growing outbreak as it emerges.

Dr. Parrish says:

“So far there are no commercial vaccines available against the H3N2 canine influenza virus, although experimental vaccines have been described. Vaccines against the H3N8 influenza virus – which has existed in this country for more than a decade – are available, but there are differences in the genetic sequences of the two strains that suggest that these vaccines would be poorly effective, or ineffective in protecting dogs against the H3N2 virus infecting dogs in the Midwest.”

“The H3N2 influenza virus emerged in Asia among dogs suffering from respiratory disease in 2006 and 2007. This canine virus likely arose through the direct transfer of an avian influenza virus – possibly from among viruses circulating in live bird markets – to dogs. That virus spread widely among dogs in South Korea and in several regions of China and caused an outbreak of respiratory disease among dogs in Thailand in 2012.

“As for other species becoming infected, there have been no reports or evidence that H3N2 influenza can infect humans. We do know that H3N2 was able to infect cats under certain circumstances, and experiments with the strain circulating in Asia showed that under some circumstances cats living with H3N2-infected dogs could become infected. There’s also some evidence that guinea pigs and ferrets can become infected and shed the virus.

"There is no evidence the virus can infect humans," says Institute Director Dr. Colin Parrish. Parrish is is studying the H3N2 virus to determine its origins and to identify ways to treat or prevent infection.

“The H3N2 virus appears to generally cause a mild upper respiratory tract disease. Some more severe infections have been reported, possibly because the dogs were also infected with other respiratory pathogens. In these cases, it may be necessary to treat any bacterial infection the dog may have acquired.

“The virus can be inactivated or removed by cleaning with detergents or disinfectants. As with other influenza viruses, keeping infected dogs away from susceptible animals would be beneficial. Quarantining infected dogs for 5 to 7 days may help to slow the spread of the virus.”