The Food and Drug Administration (FDA) is advising veterinarians and farmers to discontinue the use of unapproved aspirin for treating pyrexia and pain in lactating dairy cattle. According to the American Association of Bovine Practitioners (AABP), some dairy farms have been using aspirin to treat cattle infected with highly pathogenic avian influenza (HPAI), specifically avian influenza type A H5N1.
On October 11, the FDA issued a “Dear Veterinarian” letter as a reminder that the extralabel use of unapproved drugs in food-producing animals is prohibited. The letter emphasized that there are no FDA-approved aspirin products for cattle, and veterinarians should use approved medications for controlling pyrexia and pain in lactating dairy cattle. These approved products are considered safe, effective, and have established withdrawal periods for milk and meat.
Flunixin meglumine is currently the only FDA-approved drug for managing pyrexia in lactating dairy cattle, specifically in cases related to bovine respiratory disease and endotoxemia. Additionally, Vazalore, an FDA-approved human aspirin product, can be used under certain conditions, as outlined by the Animal Medicinal Drug Use Clarification Act (AMDUCA).
To prescribe a drug extralabel, a valid veterinarian-client-patient relationship is required, an appropriate withdrawal time must be set, and only approved human or animal drugs may be used. AMDUCA specifies that a veterinarian should not prescribe a drug extralabel if an approved drug is available for the condition being treated, unless that therapy has been deemed ineffective. Because Vazalore is only available in 81 mg and 325 mg dosages, unapproved aspirin products with larger dosages are being used instead, which the FDA has clarified is not permissible.
AABP leadership recently consulted with the FDA’s Center for Veterinary Medicine for clarification. While the FDA had previously considered aspirin use to be of low regulatory concern, the increased use and availability of labeled products for treating pyrexia (such as flunixin) have led the agency to declare such use illegal.
As of October 21, H5N1 avian influenza has been confirmed in dairy cattle across 14 states, including California, Colorado, Idaho, and Michigan, among others. In cases where cattle have already been treated with aspirin, veterinarians are urged to set appropriate milk and meat withdrawal periods using their scientific judgment.
