A recent Racing Medication and Testing Consortium (RMTC) review of violation records from nine states that lowered their phenylbutazone threshold from five micograms per milliliter of plasma to the RMTC-recommended level of two micrograms reveals that fewer overages of the medication are occurring at the lower threshold.

Phenylbutazone (commonly called "Bute") is a non-steroidal anti-inflammatory medication. In most states, one non-steroidal anti-inflammatory can be administered 24 hours prior to racing to decrease inflammation and provide pain relief. In 2009, the phenylbutazone threshold was brought before the RMTC board by regulatory veterinarians who expressed concern that the medication, at the five microgram per milliliter threshold, could be hiding lameness and compromising pre-race examinations.

The regulatory veterinarians’ concerns were confirmed by Larry Soma, VMD, at the University of Pennsylvania. His 2010 review of 120 research papers on phenylbutazone, which was published in 2012, confirmed that lameness and inflammation could be altered by the presence of phenylbutazone at the five-microgram threshold at 24 hours. In response, the RMTC lowered the phenylbutazone recommended threshold to two micrograms in 2010.

The Association of Racing Commissioners International (RCI) provided records from the racing commissions of California, Florida, New Mexico, New York, Ohio, Pennsylvania, and Virginia–all of which have lowered their phenylbutazone threshold from five micrograms to two micrograms in recent years. The New Jersey Racing Commission and the Indiana Horse Racing Commissions provided records directly to the RMTC