Bird flu kills cats. Why that matters to everyone, not just pet owners

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The bird flu that's been killing flocks of wild birds and causing outbreaks in poultry and dairy cows across the United States has another unlikely victim: house cats.

More than 140 domestic cats in the country have been infected with bird flu since 2022, according to the most recent data from the U.S. Department of Agriculture.

While the likelihood of your cat getting bird flu is low, the recent increase in cats who've contracted the disease has some experts concerned that bird flu may cause the next human pandemic.

Bird flu isn't currently contagious between people, and no humans have gotten the current strain that's circulating from their cats. But the ability of a virus to jump from species to species increases the risk that it could evolve and one day jump to humans, possibly triggering another global pandemic.

While mortality rates for cats with bird flu are high, there are steps people can take to protect their furry companions, said Jane Sykes, a professor at the UC Davis School of Veterinary Medicine who's treated dogs and cats with infectious diseases for over 20 years.

“It's very easy to prevent," said Sykes, the owner of an orange tabby named Freckles. "I'm not worried about my own cat getting it."

How deadly is bird flu to cats?

Not all strains of bird flu affect cats to the same degree. However, a strain that emerged in the Netherlands in October 2020 has caused most of the bird flu cat deaths in the United States since 2022.

That strain seems "to be very pathogenic, or deadly, for cats," said Sykes. "The current estimates of mortality in cats are at least 67%." Other studies place the mortality rate even higher, between 70% and 90%.

There is no cure for the disease for cats, so the care that your cat would receive from the veterinarian for bird flu would be "supportive" at best.

“We don't have antivirals that we can use," Sykes said. "Unfortunately, because these cats have often progressed to very severe signs quickly, they've often been euthanized.”  

Still, due to the lack of widespread testing for antibodies, which would indicate that a cat survived bird flu, as well as the possibility of undetected cases, "We don't know the big picture as well as we could," said Sykes.

While the Cornell College of Veterinary Medicine announced the first pilot surveillance testing program at shelters, clinics and vet hospitals across New York state in June, there are few systematic efforts to monitor bird flu among cats across the country – leading some experts to call for additional surveillance.

How do cats get bird flu?

Unpasteurized milk and raw or undercooked meat is a major source of infection for cats, according to Ken Gordon, spokesperson for the Ohio Department of Health.

"Other potential sources of infection include exposure to infected wild birds, poultry, livestock and their environments or contaminated surfaces," said Gordon in an emailed statement.

Since rodents can also contract the disease, it's possible that some cats got bird flu from preying on mice who had the virus, according to Sykes, who described the ability of the virulent strain from the Netherlands to infect a whole range of bird and host species as "unbelievable."

"It really just doesn't seem to care what it infects," said Sykes.

Is raw meat safe for my cat to eat?

Feeding your cat raw meat or unpasteurized dairy products places them at risk of contracting bird flu and other harmful pathogens.

Earlier this year, raw pet food companies such as Wild Coast Pet Foods issued recalls after cats became sick and died after eating their raw chicken and turkey products, a month after the Food and Drug Administration required pet food manufacturers to incorporate bird flu as a hazard in their food safety plans. In 2023, outbreaks of bird flu among cats in Poland and South Korea were traced to their raw poultry diets.

"Pet owners and caretakers are encouraged to thoroughly cook meat before feeding and avoid feeding raw-based treats or diets and unpasteurized dairy products," said Gordon, from the Ohio Health Department.

Sykes said that feeding cooked, processed diets to cats not only reduces the risk of infection of bird flu, which is relatively rare, but also for other, more common bacteria like listeria and E. coli.

Sykes treats pets who get sick from being fed raw meat in her clinic on a regular basis because pet owners often fall for the promise that raw food diets are more balanced than processed food. "They might be balanced," said Sykes, "But they're still contaminated.”  

"They're heavily marketed as being healthier for dogs and cats than commercial processed diets," said Sykes. "They're not.”  

While some pet food companies use processes such as high-energy irradiation and high-pressure processing to kill pathogens without heat, to sufficiently kill bacteria, you must use high temperatures or low temperatures over a long period of time that will end up cooking the meat, said Gordon.

What are the signs of bird flu in cats?

Sykes described the signs of bird flu in cats as a severe and rapidly progressive disease that can look similar to rabies.

"They typically are really sick, really lethargic. They don't want to move. They stop eating quickly," said Sykes. "They could be stumbling or having seizures or circling.” 

Other signs are difficulty breathing, a puffy face, blindness, and jaundice. Other cats with bird flu have been found dead because the illness progressed so quickly.

Can bird flu travel from cats to humans?

The Centers for Disease Control and Prevention considers the possibility of cat-to-human transmission of bird flu to be low, and so far, "there's been no evidence of cat-to-cat or cat-to-human transmission of an H5N1 virus," said Sykes. "That's the good news."

However, in 2016, one case of transmission was reported for a different strain of bird flu virus, H7N2, when a veterinarian in New York City became ill from treating a cat with the virus.

The concern among infectious disease experts like Sykes is that a cat will become a "mixing pot" for a new virus that can be transmitted to its human owner. This could happen if a cat gets infected with two different strains of bird flu at the same time and creates a new mutated virus that's contagious among humans.

"A new virus could emerge that could be really infectious and harmful for people," said Sykes. "That's what causes pandemics."

How can I protect my cat from bird flu?

People whose cats are at the highest risk of getting bird flu are those who work with poultry or dairy cattle in the food production industry, or work with wild birds. The Ohio Department of Health recommends that those people wash their hands and change their clothes and shoes before entering a household with indoor cats.

For everyone else, here are the simple steps that Sykes recommends to prevent your cat from getting bird flu:

• Keep your cats indoors, so they don't prey on wild birds or rodents that may carry the disease.
• If you want to feed your cat dairy, make sure the dairy product has gone through pasteurization, a heat treatment process to kill bacteria.
• Remember that poultry and beef must be cooked to 165 degrees Fahrenheit, per CDC recommendations, to be safe to eat. Freezing or freeze-drying food does not kill pathogens.
• Make sure your cat is vaccinated against rabies, so that if you do see them exhibiting neurologic signs, you can rule out rabies as a cause.