A house cat is the first mammal in San Diego County to test positive for H5N1 bird flu.
The county health department notified the public Wednesday about the case, which is still under investigation and involved a domestic shorthair breed who ate food containing raw chicken before succumbing to sudden illness mid-January.
Though no human bird flu cases have been detected in San Diego County, the virus has increasingly shown up in species other than birds, with cattle now widely infected and cases sporadically appearing in felines.
Nationwide, the U.S. Centers for Disease Control and Prevention has documented 70 human cases and one death since 2024, though none have involved person-to-person transmission, which would significantly increase the risk of a pandemic. Of those who have become infected, 41 have been exposed to infected dairy cattle and 24 have worked in the poultry industry.
San Diego County is far from the only place where avian influenza has been detected in a cat. The U.S. Department of Agriculture lists 514 highly pathogenic avian influenza detections in mammals since May 2022, with 35 domestic cat cases in 2025 and other species, including mountain lions and bobcats. This year, two bottlenose dolphins, two harbor seals and a pair of red foxes have made the list.
No information was available Wednesday on the specific brand of raw cat food involved in the San Diego County cat case.
Dr. Emily Trumbull, a county veterinarian heading up the region’s efforts to prevent bird flu from spreading among the county’s livestock and pets, said that a sample of the food consumed by the cat who died in East County has been sent to a state veterinary diagnostic laboratory for testing. The county, she said, is not naming the brand of the raw cat food consumed until testing is completed. She said the food was intended for cats and was not simply cut-up raw chicken intended for humans.
The U.S. Occupational Safety and Health istration states in “quick card” advice for food handlers that the avian influenza virus “survives indefinitely while frozen and remains infectious,” emphasizing the need to cook poultry to an internal temperature of 165 degrees Fahrenheit in order to kill the pathogen.
Cat owners are advised to avoid feeding their pets raw food, and cat owners are also cautioned to limit potential exposure to situations that may put them at a higher risk.
“It is a good idea to make sure they are indoors or supervised when they are outdoors,” Trumbull said. “There could be risks from them interacting with poultry or infected dairy cattle and we know that cats like to hunt wild birds and things like that which can increase the risk.”
San Diego resident Julie Gelfat said in an email Wednesday afternoon that her heart went out to the family that lost its feline companion to H5N1.
But she said that her 5-year-old indoor cat will continue eating freeze-dried and frozen raw chicken and other meats from California-based smallbatch. The company recently posted a statement to its customers indicating that it has “no concerns” of its food being impacted. The company says that it sources its chicken from poultry suppliers “that take impeccable care of their flocks and have best-in-class prevention strategies from flock to harvest,” and that “all flocks are tested for the avian flu before harvesting and cannot be harvested if that test does not come back as negative.”
Gelfat said she has read convincing research on the health benefits of raw meat for cats and feels that smallbatch is taking the kinds of precautions necessary to prevent infection.
“We will remain, for the time being, feeding frozen and freeze-dried raw from smallbatch,” Gelfat said. “Everyone has to know what they are feeding their furry family and be comfortable with the choices we make.”
Infections in cats, and mammals generally, are of concern, added Dr. Erik Berg, assistant medical director of the county’s epidemiology and immunization services branch, because they illustrate the species-hopping capabilities of H5N1 bird flu, which has now begun to infect humans, but has not yet evolved the ability to transmit from person to person.
“It raises concerns that the virus is changing. We don’t usually see influenza in cats, and so it raises a lot of questions more than it provides answers,” Berg said. “The overall current risk to the public, the human public, is still low, but there’s certainly a concern that we’re going to see more infections in animals and different species, including humans.”
In fact, it is becoming increasingly clear that H5N1 is starting to show up among humans in San Diego County. The region’s wastewater detection system detected an H5 bird flu strain in samples taken on Sept. 1. Additional detections, Berg said, appeared on Jan. 1 and Feb. 17 of 2025. Regular genetic analysis of samples collected from local residents who test positive for flu infection have not so far discovered any H5N1 cases.
In cats, Trumbull said, symptoms of flu infection include lack of coordination, trouble breathing and lethargy.
“Just continuing to make sure that their pets are eating and drinking and acting normally and ing their vet if they have any health concerns is what’s recommended,” Trumbull said.
