Colorado has 106 dairies and approximately 200,000 dairy cows. Detections of HPAI in dairy cattle have occurred in eight other states according to USDA. On Monday, April 22, the Colorado State Veterinarian’s office received a notification of a dairy herd demonstrating clinical signs consistent with HPAI in cattle. Samples submitted to the Colorado State University Veterinary Diagnostic Laboratory tested positive for HPAI on April 24, and were confirmed by the USDA’s National Veterinary Services Laboratory on April 25.

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

Dairy cattle affected by HPAI are reported to have decreased feed intake, decreased milk production, and abnormal colostrum-like milk. cattle affected appear to recover after receiving supportive care.