H5N1 cases in a Washington cat and Dutch cows widen concern

CURRENT BRIEF VERSION: H5N1 surveillance is widening across species, with one update in Washington state and another in the Netherlands underscoring how easily this virus can move beyond birds. In Washington, an outdoor cat in Grant County died after testing positive for highly pathogenic avian influenza H5N1, with state officials reporting the cat had contact with a dead wild bird. In the Netherlands, follow-up testing on a Friesland dairy farm linked to an H5N1-positive cat found antibodies in multiple cows, suggesting prior infection even though PCR testing did not detect active virus. Dutch authorities first reported one antibody-positive cow in January after a farm cat died, and Scott Weese later noted that five cows on the same farm had tested antibody-positive, strengthening concern about spillover into cattle. (wormsandgermsblog.com)

Why it matters: For veterinary professionals, these cases reinforce two practical points: cats remain a sensitive spillover species, and cattle surveillance still matters even when animals are no longer actively shedding virus. Wageningen University reported that the Dutch cow with H5N1 antibodies had mastitis and reduced milk yield in mid-December before recovering, a pattern that mirrors signs seen in infected US dairy cattle. At the same time, a recent systematic review found 607 avian influenza infections in felines reported from 2004 to 2024 across 18 countries, with domestic cats making up most cases and PCR-confirmed infections showing a 71.3% fatality rate. International Cat Care noted that feline cases, especially H5N1, have risen sharply since 2023 alongside spread in birds and mammals, and emphasized that cats may present with respiratory signs, neurologic disease, or even blindness, while some infected cats may remain asymptomatic. The group also highlighted that most reported feline infections followed bird exposure or contaminated raw chicken, but raw milk from infected cattle has also been implicated, supporting calls for more aggressive testing and biosecurity when cats present with acute neurologic or respiratory disease and possible bird, raw food, raw milk, or farm exposure. (wur.nl)

What to watch: Watch for more farm-level serosurveillance in Europe, and for updated guidance on testing cats and dairy herds as officials try to determine whether these were isolated spillovers or signs of broader cattle transmission. For clinics and pet owners, the practical advice is also becoming clearer: avoid feeding raw poultry or unpasteurized milk, keep farm cats from drinking on-farm milk, limit access to dead birds where possible, and move quickly when exposed cats develop respiratory or neurologic signs. (wur.nl)