H5N1 updates put new focus on cats as spillover sentinels

A pair of H5N1 developments is sharpening attention on cats and cattle. In Washington state, an outdoor domestic cat in Grant County died after testing positive for H5N1, with local officials saying exposure was likely linked to contact with an infected wild bird, not pet food. In the Netherlands, follow-up testing on a dairy farm where a cat had previously tested positive found H5N1 antibodies in multiple cows, indicating prior exposure, even though PCR testing did not find active virus in the animals or milk samples that were tested. Wageningen University & Research initially reported antibodies in one cow in January, and Scott Weese later noted that the total had risen to five cows on that farm. (khq.com)

Why it matters: For veterinary professionals, the updates reinforce two practical points: cats remain a high-risk spillover species, especially when they have outdoor access or exposure to raw animal products, and feline cases may be the first signal that broader farm-level transmission has occurred. Dutch investigators said the antibody-positive cow had mastitis and reduced milk yield in mid-December, but no active virus was detected later, highlighting how easily infections can be missed if sampling happens after the acute phase. International Cat Care has also pointed to a recent review finding a sharp rise in feline H5N1 reports since 2023, with most reported infections linked to bird-to-cat transmission, commonly through eating dead birds or contaminated raw chicken, and some cases tied to cats drinking raw milk from infected cattle. The same review estimated a 71.3% fatality rate among reported RT-PCR-confirmed feline infections, while noting cats can also be infected without obvious signs. (cms.agr.wa.gov)

What to watch: Watch for additional serology results, more farm-level surveillance in Europe, and whether veterinary and public health agencies update guidance for cats with outdoor, wildlife, dairy, or raw diet exposure. Practical prevention messaging may also get more specific, including advice to avoid raw poultry and unpasteurized milk, keep farm cats from drinking on-farm milk, promptly remove dead birds, and reduce hunting opportunities for outdoor cats. (ecdc.europa.eu)