Highly pathogenic avian influenza (HPAI) was a key topic at the Western Dairy Management Conference recently held in Reno, Nev. Jennifer Spencer, Texas A&M dairy extension specialist, and Beth Galbraith of Microbial Discovery Group, shared factors and opportunities to consider as the industry continues to gain knowledge on HPAI.

• Diagnostics and data: Using herd monitoring tools and technologies can help detect the virus before cows show clinical signs. Using rumination monitors, several dairies have found rumination dropped five days before seeing clinical signs.
• Coinfections: Testing has found that 61% of the time, a coinfection was found with HPAI. The most common have been E. coli and salmonella, suggesting that when the HPAI virus is present, other issues are occurring to bring the immune system down. Some key actions to consider include attention to transport and comingling of animals, focus on biosecurity, and improving nutrition and gut integrity to promote a more resilient microbiome in the cow.
• Vaccinations: While vaccines for HPAI remain in field studies and are not yet commercially available, Spencer and Galbraith supported the opportunity for herds to consider vaccination when it becomes available.

Another session focused on HPAI, presented by Kay Russo, D.V.M., discussed the additional implications of the virus for the industry to consider.

• Flu viruses change over time. Flu viruses are RNA viruses, meaning each time they divide, they can change properties slowly. If two flu viruses enter the same host, genetic reassortment allows the virus to make more rapid changes and the virus can become stronger. Waterfowl migration is moving the virus across regions, complicating the issue.
• In a recent study, 76.1% of seropositive cows were subclinical. The implications for spread are significant, as cows did not show signs of illness.
• Calves are showing clinical signs of the disease. Any waste milk fed to calves should be pasteurized, as the virus can be transmitted to calves through waste milk.

Russo added that symptoms of the virus have varied by region, and recent research has found an average cost of $950 per clinical case.