In other developments, the USDA said ground beef samples were negative for the virus and Michigan and Colorado announced emergency measures.
The FDA will test pooled raw milk to give the agency a better picture of the viral load before pasteurization.
Dairy cows make up about 7% of US beef production.
The cats started showing symptoms a day after clinical disease was noted in the cows, and about half of the cats died.
Global health groups say evolving developments, including a novel reassortant in Asia and increasing detections in mammals, require real-time monitoring.
The highest concentrations were in regions where the virus has been found in dairy herds.
The USDA says that lactating dairy cows must be tested before interstate transport.
Experts, with incomplete data, are quickly piecing together everything they can from the shared genetic sequences.
The researchers urge caution in feeding shot wild birds to captive carnivores during outbreaks in wild birds.
In other developments, antiviral susceptibility testing shows that H5N1 is susceptible to neuraminidase inhibitor antiviral drugs.