H5N1 updates put cats and Dutch cattle back in focus

A fatal H5N1 infection in a Washington state cat and the detection of H5N1 antibodies in a dairy cow in the Netherlands are adding to the evidence that this virus keeps finding new ways into companion animals and livestock. Scott Weese flagged both developments in recent Worms & Germs posts, noting that the Washington cat was an outdoor cat, which makes wild-bird exposure plausible, while the Dutch cow appears to have had prior exposure without evidence of active infection or spread through the herd. Dutch investigators said the cow was identified after H5N1 had already been confirmed in a cat on the same dairy farm, and follow-up testing found no virus in the cow or milk samples. (wormsandgermsblog.com)

Why it matters: For veterinary teams, the updates reinforce two practical points: cats remain highly susceptible to H5N1, and cattle surveillance can turn up evidence of exposure even when animals aren’t clinically ill. A 2025 systematic review found 423 PCR-confirmed avian influenza infections in felines, with a 71.3% case fatality rate, and researchers called for closer monitoring of cats because they often live at the animal-human interface. CDC and FDA guidance also continues to warn against exposing cats to raw milk, raw meat, or infected wildlife, and recommends H5N1 stay on the differential for cats with acute neurologic or respiratory signs plus compatible exposure history. (academic.oup.com)

What to watch: Watch for more farm-level surveillance data, especially whether European cattle investigations remain limited to isolated antibody findings or begin to show active infection. (ecdc.europa.eu)