H5N1 avian influenza has been found in cats on a dairy farm in New Mexico where cattle were infected with the same virus. As part of the farm investigation, some (number not reported) sick (type of illness not reported) cats were tested, and three were positive. There’s no way to know for sure, but I’d guess that the cats were infected by the same source as the cows (i.e. from infected wild birds), not from the sick cows themselves.

It’s totally unsurprising, since there are various reports of cats from several countries around the world being infected with this virus, which continues to circulate widely in the wild bird population. Cats hunt birds, and birds that are sick with avian flu are a lot easier to catch. Eating a sick bird is a clear way to get infected, so it’s not surprising at all to find infected cats in areas where there’s lots of flu activity. I’d guess there have been hundreds of infections of cats worldwide, but most of them have gone unrecognized.

This isn’t a game changer, but it’s yet another reminder to pay attention. Fortunately, cats (like cows) don’t have their own influenza A virus, and they tend not to be very susceptible to human flu strains. So, there’s less risk of them being infected with the H5N1 virus and another flu virus at the same time, and acting as a mixing vessel for creation of a new, more problematic recombinant flu strain. However, every spillover into any mammal poses some extra risk, and cats are potential bridges between wildlife and people, since people often have close contact with cats. That’s why we’re on the lookout for these spillover infections, and ideally want to limit exposure of cats to infected wild birds.

If you have cats that go outside and you can’t prevent that (not all cats can be indoor only), be on the lookout for flu. If an outdoor cat gets sick, especially with respiratory or neurological disease, and it’s had potential contact with flu-infected birds, it’s important to talk to your veterinarian (and ideally get the cat tested so we can gather more information on the virus’ behaviour, and also try to contain the infection).