H5N1 updates put new focus on cats as spillover sentinels
Two new H5N1 signals, one involving a dead cat in Washington state and the other involving dairy cattle in the Netherlands, are adding to the evidence that companion animals can be both victims of spillover and useful sentinels for what’s happening on farms. In Grant County, Washington, a domestic outdoor cat died after testing positive for H5N1, with officials saying the likely source was contact with an infected wild bird. In the Netherlands, investigators tracing a feline H5N1 case on a dairy farm found antibodies in several cows, suggesting prior infection even though no active virus was detected during later testing. (khq.com)
The Dutch case builds on an earlier pattern that veterinarians have been watching closely since H5N1 expanded into U.S. dairy cattle in 2024. Wageningen Bioveterinary Research reported on January 23, 2026, that one cow on a Friesland dairy farm had antibodies against H5N1 after a cat from the same farm had tested positive. The cow had reportedly shown mastitis and reduced milk production in mid-December, then recovered. All sampled cows were PCR-negative at that stage, and authorities said milk from the farm was restricted to pasteurized products while the investigation continued. (wur.nl)
Scott Weese’s February 2 update added an important wrinkle: five cows on that same farm had now tested positive for H5N1 antibodies. That doesn’t prove ongoing cow-to-cow spread, but it does strengthen the case that cattle on the premises were exposed at some point, and that a cat infection may have been an early warning sign rather than an isolated event. Wageningen also said this was the first reported detection of avian influenza antibodies in cattle in the Netherlands, and the first such report in Europe. (wormsandgermsblog.com)
The Washington cat case points to a different, but equally relevant, route of exposure. Local reporting and state tracking documents indicate the Grant County cat was confirmed in January 2026 and was believed to have been infected through contact with wild birds. That distinction matters because Washington had already dealt with feline H5N1 cases linked to contaminated raw pet food in February 2025. State guidance for companion animal veterinarians says cats are most likely to become infected on infected poultry or dairy farms, by ingesting infected wild birds, or by consuming contaminated raw products such as raw milk or raw pet food. (khq.com)
Expert and industry commentary is converging on the same message: feline H5N1 infections are still uncommon overall, but they’re serious and likely underdetected. International Cat Care’s response to a recent review highlighted a marked increase in feline H5N1 cases since 2023 and noted that infections have been reported worldwide, most often in Asia, followed by Europe and North America. The group also emphasized that most reported feline infections appear to stem from bird-to-cat transmission, especially after cats eat dead birds or contaminated raw chicken, though some cases have been linked to cats drinking raw milk from infected cattle. The underlying systematic review found that reported RT-PCR-confirmed feline infections carried an estimated 71.3% fatality rate, while also noting that cats can be infected without obvious illness and that testing bias likely favors detection of severe or fatal cases. Clinical signs most often included respiratory disease, neurologic abnormalities, and sometimes blindness. International Cat Care also flagged the small but important zoonotic concern: the review discussed outbreaks in tigers in Thailand and at a cat shelter in New York where human infection was linked to sick felids. Cornell’s feline health experts have similarly emphasized that cats with H5N1 exposure can deteriorate quickly and that surveillance in cats may help clarify the virus’s spread across animal populations. (pmc.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, these cases underscore that cats aren’t just incidental spillover hosts. They can be clinically important sentinels, especially on mixed-species premises or in households where outdoor exposure and raw feeding are part of the history. The Dutch investigation suggests that if a cat on or near a dairy operation tests positive, it may be worth asking harder questions about cattle exposure, milk handling, wildlife contact, and timing of sample collection. The fact that the Dutch cows were antibody-positive but PCR-negative also highlights a surveillance challenge: by the time illness is recognized, active shedding may have ended, leaving only serologic evidence. (wur.nl)
For small animal and mixed animal practitioners, the practical takeaway is unchanged but more urgent: ask about outdoor access, wild bird contact, farm exposure, raw diets, and raw milk; use appropriate PPE when H5N1 is on the differential; and coordinate early with animal and public health authorities when feline neurologic or respiratory disease fits the exposure history. Washington’s guidance states there is no evidence of cat-to-cat or cat-to-human transmission in the cases investigated there, but the zoonotic context still warrants caution, especially for clinic staff and pet parents handling suspect animals. The prevention advice highlighted by International Cat Care is straightforward and aligns with that risk picture: avoid feeding raw poultry or unpasteurized milk, prevent farm cats from consuming on-farm milk, safely dispose of dead birds, and try to reduce hunting and bird predation where possible. (cms.agr.wa.gov)
What to watch: The next key signals will be whether Dutch serology or surveillance identifies additional exposed cattle, whether more feline cases reveal hidden transmission on farms, and whether agencies broaden recommendations for testing cats as part of H5N1 investigations in livestock settings. It will also be worth watching whether public-facing guidance becomes more explicit about prevention in cats, including raw feeding, raw milk exposure, and practical steps to limit hunting-related contact with wild birds. (ecdc.europa.eu)