Q: My horse receives 25 milligrams of Previcox daily to manage pain related to navicular syndrome. Is long-term use of this drug okay? —Kari, via e-mail
A: Previcox is the small-animal approved formulation of firocoxib. Equioxx, which comes as an injectable or oral paste, is the FDA-approved firocoxib formulation for treatment of pain and inflammation related to osteoarthritis in horses. There seems to be some use of Previcox in horses, most likely due to cost differences. But, because there’s an FDA-approved equine formulation, this use is considered illegal.
Hypothetically, the use of 25 mg of firocoxib is approximately a half-dose for a 1,000-pound horse. Firocoxib is a “COX-1 sparing,” or COX-2 selective, nonsteroidal anti-inflammatory drug (NSAID). COX-1 is an enzyme that plays a role in protecting gastrointestinal linings and renal tissues (among other actions). Many NSAIDs inhibit both enzymes, potentially causing some of the negative side effects associated with drugs such as phenylbutazone, flunixin, and ketoprofen. Firocoxib is better suited for long-term use in the horse compared to the nonselective options.
However, I still try to avoid daily, long-term use of NSAIDs if at all possible. I often have clients give a few days with no treatment to break up a long-term protocol. Each horse is individually different and many will not have any issues; however, the risk is still present to have problems develop, such as stomach ulcers. I recommend monitoring the h