H5N1 updates put cats and cattle surveillance back in focus

H5N1 surveillance is surfacing two signals veterinarians shouldn’t ignore: a fatal cat case in Washington State and expanding evidence of prior infection in Dutch dairy cattle. In a February 2, 2026, update, Scott Weese reported that an outdoor cat in Washington tested positive for H5N1, while a dairy farm in Friesland, the Netherlands, where a cat had already died with confirmed H5N1, later showed antibodies in five cows. Together, the cases underscore how cats can flag local transmission risk and how cattle infections may only become visible after the virus is no longer detectable by PCR. (wormsandgermsblog.com)

The Dutch case has been building for months. In late 2025, attention focused on kittens from a Dutch dairy goat farm that likely died from H5N1, and subsequent investigation traced concern to a Friesland dairy operation where one cat tested positive. Wageningen University & Research reported on January 23, 2026, that one cow on that farm had H5N1 antibodies in milk, consistent with past infection, after showing mastitis and reduced milk production in mid-December. No virus particles were found in that animal, and none of the initial cattle samples were PCR-positive. (wur.nl)

What changed in the latest update is scale. Weese reported that antibody-positive cows on the farm rose from one to five, making a false positive explanation less likely and strengthening the case that cattle were genuinely infected. He argued that five seropositive animals make repeated independent bird-to-cow spillovers less plausible than at least some cow-to-cow spread, though he stopped short of calling that proven. A UK risk assessment similarly said it remains unclear whether the Dutch findings reflect limited cattle transmission or several separate exposures from a contaminated source, including wild birds or the infected cat’s environment. Importantly, both Dutch and UK sources said there was still no evidence of active viral circulation on the farm when follow-up milk and blood samples were tested. (wormsandgermsblog.com)

On the feline side, the Washington case fits a pattern that has been developing across North America. Washington State veterinary guidance from February 28, 2025, said cats are especially vulnerable to H5N1 after exposure to infected birds, dairy environments, raw milk, or contaminated raw pet food, and noted there was no evidence at that time of cat-to-cat or cat-to-human transmission. The state had already investigated indoor cats infected after eating contaminated commercial raw food, with preliminary typing suggesting a cattle-associated B3.13 genotype in those cases. That context matters because it broadens the differential for veterinarians beyond wildlife exposure alone. (cms.agr.wa.gov)

Outside reaction has been consistent: experts want more attention on cats. A University of Maryland-led review, covered by CIDRAP and other industry outlets, identified 607 avian influenza infections in 12 feline species across 18 countries from 2004 to 2024. Domestic cats accounted for 62.6% of cases, and 71.3% of PCR-confirmed infections were fatal. The authors warned that cats may represent an under-recognized bridge species because they live in close contact with birds, livestock, wildlife, and people. International Cat Care has also emphasized practical prevention steps for pet parents, including avoiding raw poultry and unpasteurized milk, reflecting how often foodborne exposure now appears in feline H5N1 reports. (cidrap.umn.edu)

Why it matters: For veterinary teams, these updates sharpen both case recognition and client communication. Cats with acute neurologic or respiratory signs, especially those with outdoor access, farm exposure, or raw diet histories, warrant a more deliberate H5N1 risk assessment. The Dutch cattle findings also suggest that relying on PCR alone may miss farms with recent infection if animals are sampled after clinical recovery. In practice, that means companion animal, livestock, and public health surveillance can’t stay siloed. A dead barn cat, a mastitic cow with falling milk yield, and contaminated raw feed may be pieces of the same epidemiologic picture. (wur.nl)

There’s also a food safety and occupational health angle. Wageningen said milk from the Dutch farm was diverted to pasteurized products while the investigation proceeded, and the milk from the clinically affected cow did not enter the food chain. The UK assessment noted staff tested negative for H5N1 antibodies. Those are reassuring details, but they don’t remove the bigger lesson for veterinarians: once H5N1 reaches mammals in mixed-species settings, surveillance has to move quickly and across species boundaries. (wur.nl)

What to watch: The next key developments will be whether Dutch authorities publish fuller serology or sequencing data from the farm, whether additional European cattle detections emerge through targeted monitoring, and whether U.S. veterinary guidance evolves to put even greater emphasis on cats as early-warning sentinels around dairies, poultry operations, and raw-fed households. (wur.nl)