Lowered phenylbutazone threshold levels resulting in fewer positive tests

States that have lowered the threshold level for the popular painkiller phenylbutazone have recorded a fewer number of positives for the drug since the lower levels were adopted, a racing-medication policy group said on Friday.

The Racing Medication and Testing Consortium, which studies medication issues and makes recommendations to the racing industry, said that a review of data from nine states that have adopted the lower threshold revealed a 44 percent decline in positives in the first six months of applying the lower threshold compared to the previous six months. The RMTC had recommended in 2010 that states lower the level from 5 micrograms per milliliter of blood plasma to 2 micrograms.

The recommendation to lower the threshold level was adopted after some veterinarians who are responsible for examining horses prior to races raised concerns that the 5 microgram threshold allowed horsemen to administer a dose of phenylbutazone that could compromise the vets’ ability to detect soreness or lameness. Phenylbutazone is allowed to be given 24 hours prior to a race in most jurisdictions.

“Trainers saw a 44 percent decrease in violations and regulatory veterinarians are better able to evaluate the horses,” said Dr. Dionne Benson, the executive director of the RMTC. “Overall, this change improves the safety and welfare of horses and jockeys.”

According to the RMTC, 15 states have adopted the lower threshold. The RMTC examined data on violations from California, Florida, Indiana, New Mexico, New Jersey, New York, Ohio, Pennsylvania, and Virginia.

After the RMTC adopted the recommendation, Dr. Larry Soma, an analytical chemist at the University of Pennsylvania, analyzed 120 research papers on phenylbutazone and determined that the 5 microgram level allowed for a dose that could mask pain in horses. His paper, published in 2012, gave the RMTC’s recommendation additional weight.