Although vaccination against infectious disease is a routine component of horse care, many owners still voice concerns about their horse’s risk of having an adverse reaction to these injections. For this reason, veterinarians sometimes administer non-steroidal anti-inflammatories (NSAIDs) before vaccinating horses to reduce the risk and severity of such reactions.

Researchers from the University of Kentucky (UK) recently hypothesized, however, that because NSAIDs inhibit COX inflammatory mediators, they might also inhibit horses’ immune response to vaccination. Whitney Zoll, BS, a veterinary student at Michigan State University’s College of Veterinary Medicine, teamed up with researchers from UK’s Maxwell Gluck Equine Research Center to assess NSAIDs’ effect on horses’ response to a commercially available equine influenza vaccine. She presented the results of their study at the 2013 American Association of Equine Practitioners convention, held Dec. 7-11 in Nashville, Tenn.

“Although the reasoning behind the co-administration of an NSAID with vaccination may seem sound, such treatments could affect the ability of the horse to respond to the vaccine,” Zoll explained.

In the first of the two-part study, she and colleagues employed 18 adult horses ages 2 to 5 that had been previously exposed to equine influenza. They administered the NSAID flunixin meglumine (commonly known as Banamine) to nine horses prior to vaccination, and the other nine animals served as controls, receiving only the vaccine.

In the second part of the study they employed 18 influenza-naive yearlings. They co-administered the vaccine and