Bird flu in dairy cattle: Unknowns Researchers still aren’t sure how bird flu spreads within dairy herds29 October 2024 29 October 2024 4 minute read 4 minute read By: By: Chris Wright North AmericaResearch has demonstrated that highly pathogenic avian influenza (HPAI) strains can infect dairy cows and that although the genotype B3.13 virus is found mostly in the udder and milk, it can also be found in the urine and neuronal tissue. Starting on Day 10 the number of suspect cases began to go down. In these three dairy farms, 1865 suspect cases were reported over a 14-day period, affecting 23,000 cows. A closer look at these same three dairy herds revealed that cows in their third lactation (older cows) were by far the most affected, with 1,000 cases reported. This was extraordinarily stressful for the veterinarians who were trying to do what’s best for the cows, the dairy industry, and the consumers.