H5N1 in companion animals raises new questions for vets

CURRENT FULL VERSION: H5N1 is no longer just a poultry and dairy story for companion animal practice. Recent federal guidance, case investigations, and diagnostic reports show that cats, in particular, can develop severe and sometimes fatal disease after exposure to infected birds, contaminated raw pet food, or raw milk from infected dairy cattle. That’s pushed veterinarians to think more broadly about avian influenza risk in household pets, even those that are primarily indoors. AVMA reporting has noted that since H5N1 appeared in the U.S. at the end of 2021, around 200 domestic cat cases have been documented nationally, with nearly 70 reported this year alone. (aphis.usda.gov)

The backdrop is the wider spread of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b across U.S. wild birds, poultry operations, and, beginning in 2024, dairy cattle. Investigators reported infections in cats on affected dairy farms in Texas and Kansas, where epidemiology and viral sequencing supported exposure through infected cattle and milk. In one CDC case series from Michigan, indoor cats in dairy worker households were infected, reinforcing that companion animal exposure can happen indirectly through contaminated clothing, equipment, or other household pathways tied to livestock work. AVMA coverage has also emphasized that avian migration patterns continue to shape case activity and that spillover into prey species such as house mice may sustain predation-related risk for cats. (wwwnc.cdc.gov)

The clearest recent companion animal warnings have centered on foodborne exposure. In December 2024, Oregon officials announced that a house cat died after eating Northwest Naturals raw frozen turkey pet food, with testing showing a genetic match between virus in the food and the cat. In January 2025, FDA said cat and dog food manufacturers using uncooked or unpasteurized poultry or cattle ingredients must reanalyze their food safety plans to account for H5N1 as a known or reasonably foreseeable hazard. FDA has since also alerted pet parents about H5N1 contamination in certain lots of RAWR Raw Cat Food Chicken Eats. AVMA reporting added that cats in San Francisco and Los Angeles died after eating a contaminated raw chicken diet carrying genotype B3.13, and highlighted a practical concern for clinics and clients alike: H5N1 may remain viable for extended periods in frozen or refrigerated raw diets, meaning products with distant sell-by dates can continue to pose risk long after purchase. (apps.oregon.gov)

Academic and public health researchers have added more detail on what illness can look like in cats. A 2025 CDC Emerging Infectious Diseases report described three domestic cats exposed to contaminated raw milk in the United States; two died after a course consistent with H5N1 infection, while a third survived after hospitalization and supportive care, including oseltamivir. The authors concluded that veterinarians should consider H5N1 when cats present with acute neurologic signs and a history of exposure to wild birds or ingestion of raw poultry or dairy products. Cornell’s Animal Health Diagnostic Center has separately advised veterinarians to consider testing neurologic cats with compatible exposure histories, including raw milk, raw meat, bird contact, or farm exposure. (wwwnc.cdc.gov)

Expert and agency messaging has become more consistent: avoid raw exposure pathways, and treat suspect feline cases with heightened biosecurity. USDA says cats can be exposed through infected birds and through unpasteurized or raw milk from infected cows. CDC guidance for veterinarians and veterinary staff recommends PPE for evaluation and specimen collection in suspected cases, and monitoring of exposed personnel for 10 days after their last exposure. AVMA policy also supports pasteurization of milk sold to consumers, which aligns with the growing concern around raw dairy as an H5N1 vehicle. (aphis.usda.gov)

Why it matters: For companion animal veterinarians, this changes both triage and client education. Cats with sudden neurologic disease, blindness, seizures, respiratory signs, or rapid deterioration may warrant H5N1 questions that weren’t routine a few years ago: Does the pet eat raw food? Has it consumed raw milk? Does it go outdoors or hunt birds? Does anyone in the household work with poultry, cattle, or wildlife? AVMA reporting adds another useful counseling point: owners feeding frozen or refrigerated raw diets may assume older products are safe, but viral persistence means stored food can remain a hazard. Clinics may also need clearer internal protocols on PPE, isolation, sample handling, and public health notification, especially in regions with active poultry or dairy detections. The broader lesson is that H5N1 risk in pets is still uncommon, but when it occurs, the consequences can be severe, and the human exposure piece means veterinary teams are part of the surveillance net. (cdc.gov)

Dogs remain a smaller part of the story, but not an irrelevant one. CDC and published surveillance suggest dogs are less susceptible than cats, yet infections and serologic evidence have been documented, particularly after contact with infected wild birds. That means veterinary advice to pet parents should stay broad: keep pets away from sick or dead birds and affected livestock, avoid raw milk and raw meat diets during ongoing H5N1 circulation, and seek veterinary care promptly for compatible illness after known exposure. (wwwnc.cdc.gov)

What to watch: The next phase will likely include more case finding in cats, continued regulatory attention on raw pet food manufacturing, and refinements to veterinary testing and infection-control guidance as officials learn more about exposure routes and cross-species transmission risk. Continued seasonal shifts tied to bird migration, plus the possibility of exposure through prey species and long-stored raw diets, mean the companion animal risk picture may stay dynamic even when farm headlines quiet down. (fda.gov)