The CDC Just Documented Cat-to-Human H5N1 Transmission. Every Veterinary Professional Needs to Read This.

For the first time, public health investigators have documented serologic evidence of H5N1 transmission from a domestic cat to a human. The person infected was a veterinary professional. They were not wearing PPE over their mouth or eyes during the exposure. They never developed symptoms. And they almost certainly did not know it happened until a serosurvey months later confirmed it had.

That combination of facts — silent transmission, occupational exposure, no clinical illness, confirmed serology — is exactly why this report matters and why it deserves more attention than it has received.

What the investigation found

Last spring, investigators with the Los Angeles County Department of Public Health and the CDC examined a cluster of H5N1 infections in domestic cats across the Los Angeles area. All 19 cats in the study had become sick after consuming commercially purchased raw milk, raw meat, or raw pet food between November 2024 and January 2025. Nine were tested and all came back positive for H5N1 clade 2.3.4.4b, genotype B3.13, the same genotype involved in the majority of human H5N1 infections documented during this outbreak period.

Investigators interviewed 139 people connected to those cats, including pet owners, veterinary staff from ten practices where 14 of the cats had been evaluated, animal control personnel, and a local health department employee. Thirty people reported flu-like symptoms after exposure. None tested positive on RT-PCR.

Months later, 25 of those individuals volunteered for serologic testing. One came back positive. That person was a veterinary professional who had direct contact with an infected cat, did not use PPE over the mouth or eyes, reported no flu-like symptoms, and had no other known risk factors for H5N1 infection. The cat had been seen at four different veterinary practices in the week before its positive result.

The study was published in the CDC's Morbidity and Mortality Weekly Report on May 7, 2026.

What this means for veterinary professionals specifically

This is not a theoretical occupational risk. It is a documented one. And the circumstances of this case are circumstances that occur in veterinary practices every day: a sick cat presenting with acute respiratory or neurologic illness, a clinician or technician providing hands-on care, PPE use that is incomplete or inconsistent because the differential diagnosis does not yet include H5N1.

That last point is the clinical crux of this report. H5N1 in cats can present as acute respiratory illness or neurologic disease. Both of those presentations walk through veterinary practice doors regularly. The reflex to consider H5N1 as a differential in a cat with acute respiratory or neurologic signs is not yet standard, and this case is a direct argument for making it one, particularly in geographic areas with known HPAI activity and in any patient with a history of raw food consumption.

The cat in this case had consumed commercially purchased raw animal products. The HPAI contamination of raw pet food has been an ongoing issue, with recalls and health warnings issued by the FDA specifically about the risk of H5N1 exposure through raw ingredients. The link between raw feeding and H5N1 in cats is not speculative at this point. It is documented across multiple cases and should be part of every intake conversation in practices that see cats.

PPE is not optional in suspected cases

The infected veterinary professional in this study did not wear PPE over the mouth or eyes. That gap is the likely exposure route. The CDC and AVMA have both published guidance on infection prevention when working with cats suspected or confirmed to have H5N1 infection, and that guidance is clear: respiratory protection, eye protection, and standard contact precautions are all indicated.

The practical challenge in veterinary practice is that H5N1 is often not on the differential at the time of initial presentation. A cat coming in with respiratory distress or neurologic signs gets handled immediately, and the full history including diet, environmental exposures, and raw food consumption may not be gathered until after the initial examination. That sequence of events is exactly how exposure happens.

The protocol adjustment this case argues for is simple but requires intention: raw food history and H5N1 exposure risk assessment should happen at triage, before the patient is in the exam room, so that PPE decisions can be made prospectively rather than retroactively.

The raw feeding conversation just got more urgent

Pet owners are advised not to feed cats raw milk or other raw animal products. That recommendation is coming from the CDC and the study authors directly, and it is grounded in a documented chain of transmission that now extends from raw commercial pet food to cats to a human healthcare worker.

This does not make every raw-fed cat an H5N1 risk. But it does mean that the raw feeding conversation, which veterinary professionals have been navigating carefully for years around issues of bacterial contamination and nutritional adequacy, now has a zoonotic public health dimension that is no longer hypothetical.

Clients who feed raw deserve to know this information clearly and without alarm. The risk to a healthy person living with a healthy raw-fed cat in a low-H5N1-prevalence area is still low. But the risk to a veterinary professional handling a clinically ill cat with an unknown raw food history and no PPE is demonstrably not zero. That distinction matters for how we talk to clients and how we protect ourselves.

The bottom line

H5N1 can transmit from a domestic cat to a human. That transmission can be asymptomatic. It can happen in a veterinary practice during routine patient care. And it can happen without the clinician ever knowing it occurred.

Take the PPE guidance seriously. Ask about raw food history at intake. Consider H5N1 in cats presenting with acute respiratory or neurologic illness, especially in areas with known HPAI activity or with any history of raw food consumption. And stay current with the AVMA's continuously updated H5N1 resources at avma.org.

This is the profession's early warning system at work. Pay attention to it.