Testing dairy cows for HPAI

On Monday, April 29, USDA required that all lactating cows being shipped across state lines have a negative test for Highly Pathogenic Avian Influenza (HPAI), what all does it mean and how does a farmer get that done?

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If you are planning to move dairy cattle, the first step is to contact your herd veterinarian. Your veterinarian will take milk samples from the cows to be shipped. USDA is providing free diagnostic testing for Highly Pathogenic Avian Influenza HPAI. In cattle, this virus is also known as bovine influenza A (BIA). Dairy producers will need to pay for the sampling and shipping, but not the tests run by qualified laboratories.

Until further notice, for lactating cows being transported interstate (and not going directly to slaughter), negative test results and a certificate of veterinary inspection are needed prior to moving those cattle. Lactating animals going directly to slaughter must be accompanied by a certificate of veterinary inspection, an owner-shipper statement, or other document that meets the applicable state requirements. No lactating animals showing clinical signs consistent with HPAI are eligible for interstate movement or movement directly to slaughter. Work with your veterinarian to ensure current requirements are being met.

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 results may take a couple more days.

Milk samples are to be collected by, or under the supervision of an accredited veterinarian, or a state licensed veterinarian, or a sample collector approved by the appropriate state animal health official. Understanding that your veterinarian may be required to take the milk samples, you should plan ahead so that the veterinarian arrives for milking and that the animals to be sampled are in one group.

Milk must be collected from each quarter as there have been some reports where only one quarter had the virus. Composite milk samples from each individual cow are needed for shipments of up to 30 animals. Do not pool samples from multiple cows. For shipments of more than 30 animals, only 30 animals must be tested.

In addition to pre-movement tests, USDA is also reimbursing qualified laboratories for testing samples from cows showing clinical signs consistent with HPAI, from cows that appear healthy in affected herds, and from other animals (e.g., cats, birds) on affected dairy farms. Your veterinarian will need approval before submitting samples in these cases. A National Premises Identification Number (PremID) is required to process all samples for HPAI.

What laboratories are running the required test? Laboratories qualified to test for HPAI are part of the National Animal Health Laboratory Network or NAHLN. If there is any question about where to submit samples, the veterinarian should contact the laboratory they usually work with or the USDA.

What if a test is not negative? The initial test results will either be “negative” or “non-negative.” A non-negative test result requires a different type of test to rule out a false positive or 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 to the confirmatory test? Positive cows and herds will be reported to USDA. A certificate of veterinary inspection (CVI) will not be issued if at least one in the herd 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 at least 30 days after the previous one.

What about other classes of animals? The Federal order that requires testing for interstate movement pertains only lactating cattle for now. The current situation is that USDA has identified spread between dairies with cattle movements, spread between cows within the same herd, spread from cows to poultry, and cows without clinical signs that have tested positive. Therefore, as the situation continues to evolve, USDA reserves the right to require testing for other classes of dairy cattle or other milk-producing farmed species that will be based on scientific factors concerning the virus and its evolving risk profile.

Containing spread of disease is always better that dealing with the outcome of wider disease spread. Likewise, dairy and beef cattle producers should increase their biosecurity to reduce the risk of introduction of this disease, as well as others, to their herds. For more information on herd biosecurity, contact your MSU Extension dairy or beef professional and talk with your veterinarian.

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