Wisconsin has confirmed its first bird flu case in a dairy herd. The virus was detected in Dodge County through routine screening under the National Milk Testing Strategy. The affected farm has been quarantined, and cattle showing symptoms are being isolated and treated.

While this is the first detection of bird flu in Wisconsin dairy cattle, the virus has already been found in the state’s poultry. A case was recently reported in neighboring Marquette County.

Bird flu in dairy cattle was first identified in the U.S. in March 2024. The first cases were reported in Texas and Kansas. Since then, more than 1,000 cases have been confirmed across 18 states. Although the rate of new detections has slowed, a recent case in California shows the virus remains an ongoing threat.

The Wisconsin case highlights broader concerns about dairy biosecurity. New research from Farm Journal reveals that while many large dairy operations report having biosecurity plans, consistent implementation and regular review are often lacking.

A survey of more than 300 dairy producers found that 68% of farms with 250 or more cows have a biosecurity plan, yet over one-third do not routinely update it. Experts stress that stronger, more practical biosecurity measures are essential to protect herds, workers and families. Officials note there is no risk to the commercial milk supply, as pasteurization eliminates the virus, and human health risk remains low.

Read more on the first case of bird flu in a Wisconsin dairy herd here.