Can My Dog or Cat Get H1N1 (Swine) Flu?

November 4, 2009 update:
Breaking News: Yes, cats can contract H1N1
See complete update history at the end of this post.

Original post date: April 27, 2009
Information about H1N1 (Swine) flu and how to protect yourself and your family is readily available.

But what about our dogs and cats? Can they catch or spread H1N1 flu to each other or members of their human family? According to infectious disease experts, at this time the answer is most likely no. This is to say that to date there are no known dog/cat to human (or vice-versa) influenza transmissions.
Critical Udate: Now that story has changed - cat confirmed with H1N1

Care should be always taken to use proper sanitation and personal hygiene in all cases of illness, and especially for the ever-changing influenza viruses.

There are two types of influenza viruses: Type A and Type B. The Type A viruses are found in humans and many types of animals, usually strains specific to that species. The type B viruses circulate widely among humans¹.

Dogs and cats do have their own versions of influenza viruses. The canine influenza virus is an influenza Type A H3N8 virus, and the feline version is Type A H5N1 influenza virus. (The numbers and letters after the type denote the numbers and types of proteins on the surface of the virus. The letter H stands for hemagglutinin and the letter N stands for neuraminidase.²)

Related Reading: New Dog Vaccine for H3N8 Flu

Who is spreading what virus? It is interesting to note that birds play an important role in the spread of all influenza A viruses. From the CDC: "Wild birds are the primary natural reservoir for all subtypes of influenza A viruses and are thought to be the source of influenza A viruses in all other animals." Read more

While rare, there have been human infections from pigs. In this current case of swine flu, a pig virus mixed with a human virus at some point in time to produce the new strain that is being passed human-to-human. This allows for quick spread of this virus in the human population. Because this is a newly created (reassorted) virus, humans do not have any immunity from previous exposures as with "regular" viruses.

Back to dogs and cats While they both have influenza Type A viruses that can infect and cause illness in dogs and cats, humans are not as similar of a species to share these viruses in the current forms. There have been no reports yet of any cases that have spread to humans or from humans to pets.

Read more about influenza viruses in dogs and cats:
H5N1 infection in domestic cats and a stone marten - Europe - from the CDC

Summary: "To date, there is no evidence that domestic cats have a role in the natural transmission cycle of H5N1 viruses" and "the European Center for Disease Prevention and Control has issued preliminary recommendations for cat owners living in H5N1-affected areas. These include keeping domestic cats indoors to prevent exposure to potentially infected birds and avoiding contact with semi-domestic and feral cats living outside the home." Report from the CDC

Key Facts about Canine Influenza (Dog Flu) - from the CDC

Summary: "To date, there is no evidence of transmission of canine influenza virus from dogs to people and there has not been a single reported case of human infection with the canine influenza virus. However, human infections with new influenza viruses (against which the human population has little immunity) would be concerning if they occurred. Influenza viruses are constantly changing and it is possible for a virus to change so that it could infect humans and spread easily between humans." CDC Key Facts Sheet

What about pet pigs?
According to the AVMA Flu FAQ: "To date, the 2009 H1N1 virus has not been reported in pot-bellied pigs. However, the possibility of human-to-pig transmission of the virus warrants extra caution by pig owners."

What about birds?
In August 2009,  it was reported that turkeys in Chile were infected with the H1N1 virus. It is believed that, as with swine, the turkeys were infected by a human source. It is not known at this time if humans can be infected from birds.

If your pet is sick
As always, if you suspect that your dog or cat is sick, please contact your veterinarian directly for an examination and to discuss any questions. Always use good sanitation practices (wash hands, etc.) when dealing with animals.