May 4, 1968 – First Horse Disqualified from Kentucky Derby for Banned Substance

Dancer’s Image became the only winner in the Kentucky Derby’s 134-year history to be disqualified for using a banned substance when traces of phenylbutazone, a non-steroidal anti-inflammatory drug (NSAID), were found in his urine sample after the race. Phenylbutazone was made legal at the Kentucky Derby by a judge’s ruling in 1971.