COX-2 Selective Drugs Considered Safe for Horses

Following the release of human clinical trial data demonstrating the link between pain-relieving medications known as COX-2 inhibitors and an increased risk of heart attack and stroke, the U.S. Food and Drug Administration recently issued a public health advisory recommending limited use of the drugs. The advisory, which also covers various non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin, ibuprofen, and naproxen, was issued as an interim measure pending further review of available data.

According to Anthony Blikslager, DVM, PhD, associate professor of equine surgery at North Carolina State University, humans should take these warnings to heart, but it isn't necessary to have the same level of concern for animals, including horses.

"Horses rarely have heart attacks, for several reasons," Blikslager explained. "For starters, they have very few risk factors for cardiovascular disease. They don't smoke or have extremely sedentary lifestyles, and they typically don't eat unhealthy diets."
Blikslager said while it is possible for a horse to suffer a heart attack, it is very unusual. "When it happens," he said, "it is usually caused by the rupture of a heart valve or major artery after strenuous exercise, and it is seldom associated with the administration of a drug."

Cyclooxygenase-2 (COX-2) is an enzyme responsible for causing inflammation and pain in the body. The enzyme cyclooxygenase-1 (COX-1), on the other hand, is associated with many beneficial functions, including production of the protective mucous lining of the stomach.

Because traditional non-steroidal anti-inflammatory drugs inhibit both COX-1 and COX-2, they are notorious for causing stomach upset in humans and horses, and occasionally, ulcers and gastrointestinal bleeding. COX-2 drugs, including the human drugs Vioxx (rofecoxib) and Celebrex (celecoxib), selectively inhibit production of the inflammation-causing COX-2 enzyme, leaving the COX-1 enzyme free to perform its protective functions in the gastrointestinal tract.

Currently, COX-2 selective drugs are not available on the equine veterinary market, although they are being used experimentally in horses in research settings. Blikslager and his team are working to develop a COX-2 drug that can be administered intravenously to equine patients.

Blikslager predicts that COX-2 selective agents will be available for clinical use in horses in the near future. "With the COX-2 inhibitors being pulled from the human drug market, this could be an excellent opportunity for horse owners," he said. "The horse might be the ideal candidate for this class of drug."

In the meantime, traditional non-steroidal anti-inflammatory agents will continue to serve as the mainstay of treatment for pain and inflammation in horses. "When you use these drugs, you have to be on the lookout for gastrointestinal problems, like ulcers or colitis, which can be fatal in horses," Blikslager cautioned. "It's important to choose the dose carefully, and to make sure that the benefits of using the drug outweigh the risks."

About the Author

Rallie McAllister, MD

Rallie McAllister, MD, grew up on a horse farm in Tennessee, and has raised and trained horses all of her life. She now lives in Lexington, Ky., on a horse farm with her husband and three sons. In addition to her practice of emergency and corporate medicine, she is a syndicated columnist (Your Health by Dr. Rallie McAllister), and the author of four health-realted books, including Riding For Life, published by Eclipse Press and available at or by calling 800/582-5604.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More

Free Newsletters

Sign up for the latest in:

From our partners