HPAI H5N1 in U.S. Dairy Cattle Updates and Resources

Highly Pathogenic Avian Influenza (HPAI) H5N1 is a virus historically carried by wild birds and was first identified in 1996.  The virus spread to domestic poultry and caused outbreaks in 2022 on U.S. commercial and backyard poultry operations resulting in high rates of mortality.  In March 2024,  HPAI H5N1 was identified in lactating dairy cattle on a dairy farm in Texas.  Much is unknown about how the virus spreads in cattle.  The virus appears to concentrate in the mammary tissue and may be shed in the milk of lactating dairy cattle.  There has been one confirmed case of HPAI H5N1 in a human that had contact with infected cattle in Texas.  These infections have been non-fatal and have had a 100% recovery rate.  Currently, there have been no confirmed cases of HPAI H5N1 in dairy cattle in Vermont or surrounding states.

Animal Health Considerations

Among the confirmed cases of HPAI cattle, most likely to be infected are older (second lactation and greater) that are in mid to late stage of lactation. Clinical signs of the virus in lactating cattle include decreased feed intake and milk production, thickened milk that may look like colostrum, fever, nasal discharge, and changes in manure texture and consistency.  Symptomatic animals should be isolated from healthy animals and treated with supportive therapy associated with depressed rumen activity and dehydration.  These cattle fully recover within 2-3 weeks.

A fact sheet on HPAI H5N1 in U.S. Dairy Herds is available on the Northwest Crops and Soils website and linked here: Highly_Pathogenic_Avian_Influenza_H5N1_in_U.S._Dairy_Herds_April2024.pdf (uvm.edu)

Milk Supply Safety

Pasteurized milk and other dairy products, infant formula and beef have all tested negative for live or infectious HPAI virus.  Additional testing and research efforts by the USDA’s Food Safety and Inspection Service (FSIS) and the Food and Drug Administration (FDA) continue.  The commercial milk supply is safe.  Milk and meat from unhealthy animals are prohibited from entering the food supply. 

Federal Order and Interstate Transport Guidelines

A Federal Order announced by the USDA was made effective on April 29th to better track and understand any spread of HPAI H5N1 in livestock.  The order requires that all lactating cattle traveling across state lines test negative for the virus within 7 days of transport and move with a Certificate of Veterinary Inspection.  Interstate movement of lactating cattle to slaughter facilities (without any interim stops) may travel with Owner Shipper Statement documentation, which must be submitted to both the origin and destination state.  Lactating animals exhibiting any signs of illness are prohibited from interstate transport.

The Owner Shipper Statement Form is available here: National OSS fillable form effective April 30, 2024.pdf (vermont.gov).  In Vermont this completed form should be emailed to agr.animalhealth@vermont.gov or stephanie.parks@vermont.gov

Additional details regarding interstate movement of lactating dairy animals are available on the Northwest Crops and Soils website and linked here: HPAI_H5N1_In_Dairy_Cattle_Update_and_Federal_Order_5.2.24.pdf (uvm.edu)


Contact your herd veterinarian if you have animals exhibiting HPAI H5N1 symptoms or healthy animals that need to be transported across state lines.  A licensed veterinarian may submit milk (composite sample with milk from all 4 quarters) or nasal swab samples to be processed only by an approved National Animal Health Laboratory Network (NAHLN) facility.


Implementing a biosecurity plan on your dairy farm offers a greater level of protection against exposure to a variety of threats.  Much is still unknown about how HPAI H5N1 is spread.  In addition to standard farm biosecurity practices, precautions should be taken when handling symptomatic livestock and their milk, traveling between farms, or moving animals between farms.  A full list of disinfectant products that are effective against HPAI, including the active ingredients, product names, and required contact times is available on the Environmental Protection Agency (EPA) website EPA’s Registered Antimicrobial Products Effective Against Avian Influenza [List M] | US EPA

Dairy Biosecurity Recommendations for HPAI are available here: Dairy Biosecurity Recommendations for HPAI and More (aabp.org)

Resources for creating a biosecurity plan for your farm are available on the Healthy Farms Healthy Agriculture website Biosecurity Plan – Healthy Farms Healthy Agriculture and the National Milk Producers Federation (NMPF) website Biosecurity – National Dairy FARM Program

Leave a comment

Skip to toolbar