Despite its availability, aspirin has never gone through the process of being approved by the Food and Drug Administration (FDA) for use in cattle. However, FDA considered aspirin to be of “low regulatory concern,” so its use in scenarios where a veterinarian determined there to be no other option for treatment was acceptable. The agency has now reversed that stance and released a letter to veterinarians this week emphasizing that aspirin use in dairy cattle and other food animals is prohibited.
Other relatively common dairy treatments, including lidocaine, epinephrine, and calcium solutions, are also technically unapproved. Drugs are typically unapproved because they are low revenue and companies do not see a return on the lengthy, expensive FDA approval process, said Alison Vander Plaats, D.V.M., on an episode of the American Association of Bovine Practitioners (AABP) podcast, “Have You Herd?” Unapproved drugs may still be used in therapeutic cases on an individual animal basis when there is no approved option for treatment and they are considered of low regulatory concern, meaning they are likely safe. This is the category aspirin has fallen into for years.
So why the change in FDA’s position?
“The major impetus for this is the highly pathogenic avian influenza (HPAI) outbreak in California has resulted in a big uptick of aspirin use for the relief of pyrexia (fever),” said Vander Plaats, who formerly practiced in California and chairs AABP’s committee on pharmaceutical and biologic issues.
Even with approved drugs, she emphasized that the tolerance for residues is zero. With an unapproved drug, the concern for residues is even higher, and if more animals are being treated with this drug, the chance of a drug residue incident occurring is exacerbated. Vander Plaats noted that FDA has been receiving comments concerned about how HPAI-infected farms are handling treatment and the risk to the food supply. While we know pasteurization kills the virus in milk, we must also give consumers confidence there are no drug residues in milk.
With these concerns, the decision was made possible by the fact that there are FDA-approved treatments for pyrexia, including injectable and pour-on flunixin options. “Because there are approved drugs with labelled indications, those should be our first line of treatment,” Vander Plaats said.
What can vets and farmers do?
In the wake of this shift, Vander Plaats encouraged veterinarians to review their protocols to ensure they are compliant and recommend approved drugs wherever possible. Then, take that one step further by making the effort to review what is actually being followed on farms. “Protocol drift is a real thing,” she noted, and farm employees may be switching things up on their own.
Farms infected with HPAI are sometimes treating hundreds or thousands of cows at a time, she said. It is easy to want to throw everything at them, but she reminded veterinarians to go back to the basics. Most of these cows are dehydrated and off feed, so fluid therapy is often going to be the best place to start. From there, some cows may have extremely high fevers and require more intense treatment. Vander Plaats said that’s when to look at approved nonsteroidal anti-inflammatory drugs (NSAIDs) like flunixin. Don’t forget to adjust withdrawal periods, too, in times of any extra-label usage.
