Like many influenza viruses, the H1N1 virus has crossed species lines, infecting pigs, ferrets, humans and some cats -- including a cheetah at a California zoo. While veterinarians have reported several cases of the infection in cats, they've only reported a few cases of the virus in dogs. While flu viruses mutate rapidly, and scientists cannot rule out the possibility occurring in the future, no occurrences of dog-to-human transmission of the virus have been reported.
Chinese scientists reported the first two cases of the H1N1 virus in dogs in November 2009. However, the American Veterinary Medical Association won't confirm this, as they could not gain access to the dogs or the results of any tests. However, in December of the same year, researchers confirmed that a dog from New York had the virus. The dog -- who eventually recovered with veterinary care -- caught the virus from its owner, whom doctors confirmed had H1N1. In addition to H1N1, dogs can get their own version of the flu, called H3N8, which likely originated in horses before mutating into its current form.
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