H5N1 updates put cats and Dutch dairy surveillance in focus

H5N1 surveillance picked up two signals veterinarians will want to keep on their radar: a fatal infection in an outdoor cat in Washington state, and expanding evidence of prior H5N1 exposure in dairy cows on a Dutch farm tied to a cat case. Neither event is wholly surprising, but together they underscore how the virus keeps surfacing at the bird-cat-cattle interface. (wormsandgermsblog.com)

The cat side of the story fits a pattern the profession has been watching since 2024. Cats have repeatedly shown high susceptibility to H5N1, with exposures linked to infected wild birds, raw poultry diets, and raw milk. A 2025 systematic review in Open Forum Infectious Diseases estimated a 71.3% fatality rate among reported RT-PCR-confirmed feline infections, and University of Maryland researchers said surveillance in cats is urgently needed because reported cases have climbed sharply since 2023. (academic.oup.com)

The Dutch cattle finding adds a different layer. Wageningen University & Research and the Dutch food safety authority reported in January 2026 that one dairy cow on a Friesland farm had H5N1 antibodies after a cat from that farm tested positive. That cow had reportedly shown mastitis and reduced milk yield in mid-December 2025, then recovered. Follow-up testing found no active virus by PCR in sampled cows, and Dutch authorities said milk from the affected period did not enter the food chain and the farm’s milk was restricted to pasteurized use while the investigation continued. (wur.nl)

Scott Weese later reported that the antibody count on that farm rose from one cow to five cows, which strengthens the case for a spillover event into cattle, even if there is still no evidence of ongoing viral circulation. Dutch authorities have emphasized that this is not comparable to the U.S. dairy outbreak because no virus particles have been detected in the Dutch cows or their milk so far. The ECDC likewise said its risk assessment was unchanged: low for the general public, and low to moderate for people with occupational exposure to infected animals or contaminated environments. (wormsandgermsblog.com)

Expert commentary around cats has been consistent. Weese’s blog stressed that fatal feline infection is “bad” regardless of whether mortality is described as almost always or just often fatal, and pointed to limiting outdoor access during local bird activity and avoiding raw poultry-based diets as key prevention steps. Washington state guidance for veterinarians similarly advises asking pet parents about raw pet food, raw dairy, and wild bird exposure, and notes that exposed veterinary staff and pet parents may be monitored by public health after contact with infected cats. (wormsandgermsblog.com)

Why it matters: For veterinary teams, these updates argue for a broader index of suspicion. In cats, H5N1 should stay on the differential list for acute respiratory or neurologic disease when there’s any history of outdoor hunting, wild bird contact, raw poultry diets, or raw milk exposure. In food-animal practice, the Dutch case is a reminder that mild or transient bovine infections may only become visible through serology, especially if clinical signs are nonspecific, like mastitis or milk drop. That matters for farm biosecurity, staff exposure assessments, and conversations with pet parents on mixed-species farms, where cats may act as early sentinels of spillover. (content.govdelivery.com)

The bigger concern is what repeated mammalian spillovers create over time. Even when a single farm event appears self-limited, each jump into cats or cattle gives the virus another opportunity to adapt. That doesn’t mean the Dutch situation is becoming a U.S.-style dairy outbreak; that would be an inference not supported by current data. But it does support continued testing, rapid reporting, and practical prevention messaging, especially around raw animal products and wildlife exposure. (wormsandgermsblog.com)

What to watch: The next important signals will be whether Dutch follow-up testing finds additional antibody-positive herds or any PCR-positive cattle or milk, whether more wildlife-linked cat cases are reported in North America this spring, and whether veterinary and public health agencies update farm, shelter, or companion-animal testing guidance in response. (wur.nl)