Approximately 1-2 weeks after beginning to consume a batch of commercially available raw pet food purchased in Los Angeles County, one cat in a household of two strictly indoor-only cats became acutely ill. This cat had signs of inappetence followed by a rapid decline characterized by neurologic symptoms. The cat died several days after the initial signs of illness. About five days after the first cat became ill, the second cat showed signs of illness including a loss of appetite and fever that progressed to severe neurologic signs before this cat also died. This second cat was sampled for influenza A by PCR testing on swabs of the nares, oropharynx and rectum after its death. The samples were tested by the Los Angeles County Public Health Laboratory and all three were PCR-positive for influenza A. The sample was then confirmed positive for H5N1 avian influenza clade 2.3.4.4b genotype B3.13 on September 23, 2025, by the USDA’s National Veterinary Services Laboratory (NVSL). This is the genotype currently circulating in dairy cows and poultry in the U.S. The NVSL will also analyze the samples using whole genome sequencing (WGS). The owner identified the raw food product that was fed to the cats and shared the packaging and lot code information. Investigation into the food is ongoing with the U.S. Food and Drug Administration (FDA). LAC DPH is monitoring household members and veterinary clinic staff who had contact with the sick cats for flu symptoms and offering testing and treatment for persons with clinical signs. No human cases of H5 bird flu have been linked to this case to date, and the risk of virus transmission to people remains low. Veterinary Public Health extends sincere condolences to the family of these cats. We sincerely appreciate the time and effort by the pet owners who provided information about their household pets, exposures and about the raw products their cats consumed. Reporting unusual occurrences of animal disease is critical to protecting the health of both animals and people in Los Angeles County.