The use of corticosteroids in racehorses has created controversy, but the medications are beneficial when used appropriately. That was Dr. Wayne McIlwraith's message during the Welfare and Safety of the Racehorse Summit IV, which was held Oct. 16 and 17 at Keeneland in Lexington.
"Proponents, of course, will say they (corticosteroids) are needed to decrease inflammation, musculoskeletal pain, ongoing joint degradation, and opposite limb overload," said McIlwraith during his presentation on the summit's opening day. "The opponents will say they are merely masking pain and lead to joint deterioration. I'm obviously in the first camp, the proponents of corticosteroids. They have a substantial place in the practice of veterinary medicine. But there are side effects with some products. Not all corticosteroids are the same."
McIlwraith, who is based at Colorado State University and is a pioneer in the field of equine orthopedic research and surgery, included a review of research on corticosteroids.
"Depo-Medrol (methylprednisolone acetate) reduces lameness, but also causes a significant increase in cartilage degradation," he said. "That problem isn't seen with other products such as Vetalog (triamcinolone acetonide) and Celestone Soluspan (betamethasone sodium phosphate and betamethasone acetate).
"Depo-Medrol is bad; the others are good. That's the bottom line," said McIlwraith.
Veterinarians administer corticosteroids to racehorses most commonly through intra-articular joint injections. This group of medications is potent and long-lasting, which raises regulatory issues.
"That is hugely important when we start discussing the need for the use of them very close to competition," McIlwraith said. "There needs to be a point where therapy ends and competition begins. That is part of the dilemma we have."
The New York State Racing and Wagering Board recently enacted a series of new medication rules based on recommendations from a task force on racehorse health and safety. Under those rules, the administration of corticosteroids systemically is prohibited within five days of a race. The medications also can't be injected into a horse's joints within seven days of a race. In addition, intra-articular Depo-Medrol can't be given within 15 days of a race.
McIlwraith suggested following his talk that regulators should be even stricter.
"At the moment, they're saying seven days, but you could make it 14 days without a problem for the so-called shorter-acting corticosteroids because they are still effective (therapeutically)," he said. "You would take away all those concerns about a horse being blocked (from feeling pain) and that kind of thing."
McIlwraith also mentioned a recent study in Australia involving corticosteroids and horses with pre-existing musculoskeletal conditions. The animals treated with the medications had a risk of injury that was five times greater than the horses that weren’t treated. However, the researchers said the higher risk most likely was due to the progression of the pre-existing conditions and that further study was needed.