DENVER (KDVR) — Bird flu has been detected in dairy cows in Colorado, the state agriculture department announced on Friday.

It’s the first time the highly pathogenic avian influenza, or H5N1, has been diagnosed in Colorado cattle, the Colorado Department of Agriculture said in a release. It brings the state among eight others where bird flu has been found in dairy cattle.

“We continue to see this ongoing HPAI outbreak evolve and over the last month have seen transmission of the virus now move into dairy cattle,” Colorado State Veterinarian Dr. Maggie Baldwin said in a statement. “While we don’t yet completely understand the mechanism of transmission of this virus, we do know that it appears to be spreading from cow to cow and between herds.”

The case comes out of northeast Colorado. The state veterinarian’s office was notified Monday about “a dairy herd demonstrating clinical signs consistent with HPAI in cattle,” according to the release. Samples tested presumptive positive on Wednesday and were confirmed by a U.S. Department of Agriculture laboratory on Thursday.

Signs of bird flu in dairy cattle

Some signs of avian flu in dairy cattle include decreased feed intake, decreased milk production and abnormal colostrum-like milk, the agriculture department said.

While affected cattle “appear to recover after supportive care,” cattle producers were urged to take action to prevent the spread of the virus.

“It is critically important that producers implement enhanced biosecurity measures to mitigate the spread of highly pathogenic avian influenza,” Baldwin said.

Is the commercial milk supply safe?

While samples of pasteurized milk have tested positive for remnants of the bird flu, consumers were reassured that the commercial milk supply is still safe.

“USDA and FDA (Food and Drug Administration) have stated that because commercial milk products are pasteurized before entering the market, at this time there is no concern about the safety of the commercial milk supply, or that pasteurized milk poses a risk to consumer health,” the agriculture department said in the release. “Pasteurization has continuously proven to inactivate bacteria and viruses in milk.”

H5N1 is primarily an issue in poultry and now in dairy cows, although two human cases have been reported: one in Colorado in 2022 and one in Texas this year.