Three black and white Holstein dairy cows are standing in a barn.

Avian (Bovine) Influenza A in Dairy Cows

Dr. Julie SmithAnimal Health, Livestock diseases

April 29, 2024


The USDA is offering free diagnostic testing for bovine influenza A (BIA H5N1). Dairy producers will need to pay for the sampling and shipping, but not the tests run by qualified laboratories.

Beginning Monday April 29, negative test results and a certificate of veterinary inspection are needed prior to moving lactating dairy cattle across state lines, if they are not going directly to slaughter. Lactating animals going directly to slaughter must be accompanied by a certificate of veterinary inspection. No lactating animals showing clinical signs consistent with BIA H5N1 are eligible for interstate movement or movement directly to slaughter.

For now, the federal order only applies to dairy cows that are producing milk, no matter what volume. When a negative test result is required, the test must be performed no more than seven days before the interstate movement occurs. Test results are generally available within one to three days. However, additional testing needed to confirm positive results may take a couple more days.

Composite milk samples (which contain milk from all working teats) from each individual cow are needed for shipments of up to 30 animals. For shipments of more than 30 animals, only 30 animals must be tested.

The USDA is also reimbursing qualified laboratories for testing samples from cows showing clinical signs consistent with BIA H5N1, from cows that appear healthy in affected herds, and from other animals on affected dairy farms.

What laboratories are running the required test? Laboratories qualified to test for BIA H5N1 are part of the National Animal Health Laboratory Network or NAHLN. Work with your veterinarian to ensure samples are sent to an appropriate NAHLN laboratory.

What is a non-negative test result? In the event that initial testing does not return a negative result additional testing is needed. Such a result is called “non-negative” instead of “positive” because a different type of test is required to confirm a positive result. Other terms that also apply to non-negative results include “suspect case” and “presumptive positive case.” A test designed to detect the specific molecular sequence of avian influenza virus matching the HPAI H5N1 clade virus is required to confirm a positive case.

What if a cow tests positive? A certificate of veterinary inspection (CVI) will not be issued if an animal tests positive. The animal must be held for 30 days and test negative prior to moving across state lines. The follow up sample must be collected no less than 30 days after the previous one.


Important Resources

UVM Extension Facts on Avian Influenza in Dairy Cows
University of Vermont Extension has developed a fact sheet on HPAI in dairy cows. Download the factsheet in PDF format here.Opens a new window
What is Your Premises Identification Number or PIN?
Do you know or have a PIN for your farm premises? Check this resource about PINs and a list of PIN contacts for all 50 U.S. states. Click here for PIN information.Opens a new window
Need a Secure Milk Supply Enhanced Biosecurity Plan?
The Secure Milk Supply Plan recommendations for enhanced biosecurity to protect the herd from diseases. Click here for enhanced biosecurity resources.Opens a new window
USDA APHIS: Highly Pathogenic Avian Influenza (HPAI) in Livestock
Stay current with U.S. HPAI detections in livestock, recommendations for veterinarians and farm workers, FDA resources and more. Click here for USDA APHIS updates.Opens a new window

Worker Protection and Farm Safety

Worker Protection and PPE

Take steps to reduce the risk of infection for avian influenza A viruses associated with severe disease when working with animals or materials, including raw milk, confirmed infected or potentially infected with these viruses.

Reduce Exposure to Influenza A VirusesOpens a new window

Biosecurity Signs for the Farm

Biosecurity signs can help protect your farm animals, workers, and visitors from bringing diseases to the farm or leaving with them on boots, clothing, etc. Download this free series of signs in English and Spanish, and print them out to post around the farm.

Farm Biosecurity Signs

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About the Author

Dr. Julie Smith

Dr. Julie Smith is a research professor at the University of Vermont. Julie received her B.S. in biological sciences, D.V.M., and Ph.D. in animal nutrition at Cornell University. Since 2002, she has applied her veterinary background to programs in the areas of herd health, calf and heifer management, and agricultural emergency management. She has taught courses in animal welfare, calf biology and management, and ABCs of biosecurity to undergraduates, mostly in the Department of Animal and Veterinary Sciences. As a veterinarian and spouse of a dairy farmer, Julie is well aware of the animal health and well-being concerns of dairy animals. Julie has conducted trainings for Extension educators, livestock producers, and community members on the risks posed by a range of animal diseases, whether they already exist in the United States, exist outside of the United States, or pose a risk to both animal and human health. In all cases, she emphasizes the importance of awareness and prevention. In addition, she has led a number of projects on biosecurity and emergency disease preparedness.

About the Editor

Joanna Cummings

Joanna Cummings received a Bachelor of Science in Horticulture from The Pennsylvania State University (PSU), with a specialization in vegetable crop and greenhouse production. At PSU, she was a research technician on no-tillage vegetable crop experiments, and a greenhouse assistant in the All-American Selections Research Gardens. Her career in the agriculture industry includes field research, work with dairy and vegetable farms, and as a greenhouse manager, estate gardener, landscaping and market garden entrepreneur. She transitioned to the science communication field after receiving a master of science degree in environmental communications from Antioch University New England. At Antioch, Joanna was a field botany laboratory teaching assistant, manager of the herbarium, and editor of the department's student newsletter, Notes and Niches. She currently works with Research Professor Julie M. Smith as a communications professional in the University of Vermont Animal and Veterinary Sciences Department. She is the webmaster for the Healthy Farms Healthy Agriculture website.