H5N1 reports in a Washington cat and Dutch cow raise new flags

A Washington state outdoor cat’s fatal H5N1 infection and the first detection of H5N1 antibodies in a Dutch dairy cow are adding to the evidence that avian influenza keeps finding new mammalian hosts, often through familiar exposure routes. Washington officials said a Grant County cat that had contact with a dead wild bird tested positive for highly pathogenic avian influenza and died, prompting renewed advice to keep cats away from wild birds and other potentially infected animals. In the Netherlands, Wageningen University & Research reported antibodies to H5N1 in milk from one dairy cow on a Friesland farm where a cat had previously tested positive; no virus particles were found in the cow, and Dutch authorities said there was no evidence of active viral circulation in the herd. (agr.wa.gov)

Why it matters: For veterinary professionals, the paired reports underscore two practical points: cats remain a sensitive spillover species, and cattle surveillance can pick up signs of prior exposure even when active infection isn’t detected. That matters because feline H5N1 cases have risen sharply in recent years, with a recent systematic review identifying 607 avian influenza infections in felines across 18 countries from 2004 to 2024, including a high fatality rate among PCR-confirmed domestic cat cases. Exposure risks highlighted by public health and animal health agencies include contact with wild birds, raw poultry, and unpasteurized milk, all of which should stay on the differential when cats present with acute respiratory or neurologic disease. (academic.oup.com)

What to watch: Watch for whether Dutch follow-up testing finds additional seropositive cattle or any active virus, and whether U.S. animal health agencies expand cat-specific surveillance and prevention messaging as spillover cases continue. (assets.publishing.service.gov.uk)