A case of highly pathogenic avian influenza (HPAI) has been detected in a dairy herd in Dodge County, Wisconsin, the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) announced Sunday. This marks the first confirmed detection of the virus in dairy cattle in the state.
The herd was identified through routine National Milk Testing Strategy screening, not the surveillance required for moving cattle across state lines. The affected farm has been quarantined, and any cattle showing signs of illness are being separated for treatment.
Bird flu has already been detected in poultry flocks in Wisconsin. On Dec. 9, state officials reported HPAI in a flock in Marquette County, which is just one county away from the affected dairy herd.
HPAI in dairy cattle has been documented in the U.S. before, with the first detections reported in March 2024 in dairy herds in Texas and Kansas. Since then, there have been more than 1,000 confirmed cases across 18 states, primarily through targeted testing and monitoring programs. While the pace of new detections has slowed in recent months, one additional confirmed case has been reported in California within the past 30 days, indicating the virus is still a threat.
HPAI Confirmed Cases in the Last 30 Days
Total HPAI Confirmed Cases
A Wake-Up Call for Dairy Biosecurity
The Wisconsin case comes as new research from Farm Journal highlights ongoing gaps in dairy biosecurity practices nationwide. A survey of more than 300 dairy producers, presented at the MILK Business Conference, found that while many operations report having biosecurity plans in place, consistent implementation and regular review remain a challenge.
According to the survey, 68% of farms with at least 250 cows say they have a biosecurity plan, yet 34% of those producers acknowledge they do not routinely review or update it. The findings point to vulnerabilities at a time when disease threats such as HPAI, New World screwworm and bovine spongiform encephalopathy continue to raise concern across the livestock sector.
“We need biosecurity efforts to be more impactful at the ground level,” said Kirk Ramsey, professional services veterinarian with Neogen, who reviewed the survey results. “Not only to prevent major outbreaks, but also to protect employees and families from what could be carried home every day.”
As emerging diseases continue to challenge dairy operations, the research reinforces the importance of consistent, practical biosecurity measures to reduce risk and protect herd health.
What are the Symptoms of HPAI in Dairy Cattle?
As monitoring continues, officials are urging producers to stay alert for early signs of illness within their herds, as prompt detection and response remain key to limiting further spread. Signs of HPAI include:
- Drop in milk production
- Loss of appetite
- Changes in manure consistency
- Thickened or colostrum-like milk
- Low-grade fever
State officials are monitoring the situation and working closely with the farm to contain the virus and prevent further spread. DATCP emphasized there is no concern for the safety of the commercial milk supply, as pasteurization eliminates the virus. The CDC considers the human health risk low.
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