Lower thresholds for the common pain reliever phenylbutazone (Bute) in post-race tests of horses could be on the way in California in spite of objections from horsemen.

At its meeting Feb. 17 at Santa Anita Park in Arcadia, Calif., the California Horse Racing Board (CHRB) approved a 45-day comment period for a rule change that would reduce the permitted level of phenylbutazone from five micrograms per milliliter of blood plasma or serum to two micrograms.

In proposing the reduction, ,Rick Arthur, DVM, CHRB equine medical director, said that the current allowable levels of non-steroidal anti-inflammatory drugs such as phenylbutazone and flunixin (Banamine) could be compromising pre-race examinations by veterinarians checking horses for soundness.

"This is a safety issue," Arthur said