Bird flu has killed dozens of cats across the world. Is your kitty at risk?

When it comes to the bird flu outbreak, a lot of attention has been placed on cows and, of course, birds — but they’re not the only animals getting infected with the H5N1 virus. Cats are increasingly at the center of this growing public health crisis, which is especially concerning given they drink milk at dairy farms and eat birds and mice, which have recently been reported as reservoirs for the virus.

When cats die from bird flu, it can be grisly. They experience fever, loss of appetite and severe respiratory and neurological symptoms that are unpleasant and painful.

As reported in the Centers for Disease Control and Prevention's Emerging Infectious Diseases journal, more than half of cats around the first Texas dairy farm to test positive for bird flu this spring died after drinking raw milk from the infected cows.

"The cats were found dead with no apparent signs of injury and were from a resident population of [approximately] 24 domestic cats that had been fed milk from sick cows," the scientists wrote. “Clinical disease in cows on that farm was first noted on March 16; the cats became sick on March 17, and several cats died in a cluster during March 19–20.”

H5N1 has been known to exist in birds since 1996, but the current situation really started to ramp up around 2021, killing hundreds of millions of them around the world in just a few years. It has also infected other mammals, including seals and bears. However, this recent outbreak in the U.S. is the first time public health officials have confirmed that the virus jumped from a cow to a human. Since the outbreak, there have been three reported human cases where people have been infected this way with bird flu — although experts say it’s highly likely there are more cases — and at least 90 dairy herds affected in 12 states.

There have also been at least 9,398 wild birds confirmed to have it. Considering that cats are predatory animals with hunting instincts, especially at times, toward birds — are domestic outdoor cats at risk for getting bird flu? And should cat owners take precautions like keeping their outdoor cats inside?

Dr. Rajendram Rajnarayanan of the New York Institute of Technology campus in Jonesboro, Ark., told Salon that experts don’t really know the “magnitude” of the situation and how it’s affecting domestic animals, like cats.

“I don’t see a big threat in terms of H5N1 spreading among domestic cats. Yes, we do have some domestic cats that have been reported,” Rajnarayanan said. “But what I would be looking at is good hygienic practices in general, and then I would suggest looking for signs of illness.”

Another area of concern to be aware of is feeding your cat raw meat. In summer 2023, a bird flu outbreak in Poland raised alarm bells when more than 45 cats in 13 geographical regions of the country died. Testing found that 29 had H5N1. Experts suspected raw meat was linked to the outbreak. Cats that have been confined indoors have also died from bird flu, as noted by a 2023 study of 40 shelter cats in South Korea, 38 of which died from duck meat cat food contaminated with bird flu.

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Daniel Goldhill, a virologist at the Royal Veterinary College, told Salon if you live on a farm and have cats that get raw milk from the cows, to be “really careful” about letting your cats consume raw milk. 

“One of the ways that vets recognized that this was avian flu had jumped into cows, which they weren't expecting, was that they also saw on various farms where the cows were getting sick they saw cats dying and birds dying as well,” Goldhill said. “That's how the majority of the cats we've seen get infected have got it — they’ve lived on farms.” 

But that’s not the only way, Goldhill pointed out. There have been reported cases of cats getting infected from wild birds directly. 

“If you have a cat that catches a bird that has bird flu, then it is possible in some cases for the cat to get avian flu,” he said. “And if the avian flu successfully replicates in the cat, it can go systemically through the cat, it can get into the cat’s brain and then the cat can die.”

Goldhill emphasized that the numbers of cats who have died this way are pretty low. When asked if cat owners should keep their outdoor cats inside, he said the possibility of bird flu is something to be aware of — especially if you live on a farm. But, in his opinion, your regular domestic cat is “probably more likely to be run over” by a car. Of course, cats can catch plenty of other diseases if they're given uncontrolled access to the outdoors, including rabies, ringworm, Salmonella and feline immunodeficiency virus (FIV), which is basically the equivalent of HIV in humans.

For years, experts have warned that if bird flu made its way to pigs, it could be time to press the panic button. That's because swine are closer to humans in genetic terms, acting as a prime reservoir for viruses to mutate into something that could turn into a far-reaching pandemic in people. Is the fact that cats are getting infected a cause for concern as well? 

“For cats, we don't really see this continued transmission, we don't see this sustained transmission in cats,” Goldhill said. “There's much less of an opportunity for the virus to spread between cats and develop traits that would let it jump into humans.”

A bigger worry, he said, are minks and ferrets. “They have receptors that look much more similar to the human receptors in their airways,” he said. Indeed, a study from the Centers for Disease Control and Prevention published Friday found that ferrets are especially susceptible to the strain of H5N1 that infected a human in Texas. The virus was 100% lethal in all six ferrets that were infected.

"This is very concerning," Rick A Bright, formerly the chief executive officer of the Pandemic Prevention Institute and an expert on influenza viruses, said on X (formerly Twitter). "Efforts to change to narrative in any way to soften this important data are reckless. Ferrets are the animal model used frequently for human infection. The fact that they got so severely ill, virus infected most of their internal organs and brain, and they died, is a strong signal that every effort to stop this virus from spreading should be considered seriously."

In other words, cats may be the least of our worries.