Steroid usage in racehorses has received a good deal of attention in the media, perhaps reaching a peak during the 2009 Triple Crown season when Big Brown won the Kentucky Derby and Preakness on the legally administered steroid stanozolol, then flopped in the Belmont without it. While no one could ever prove the steroid helped the horse win or that his loss was associated with being steroid-free, the situation added significant fuel to the fire of medication regulation in racehorses.

One of the tough aspects of regulating substances that are naturally produced in the horse’s body, such as many steroids, is that before you can decide how high a level of the substance constitutes an administered medication or abuse, you have to find out how much horses produce normally.

At the 2009 American Association of Equine Practitioners (AAEP) Convention held Dec. 5-9 in Las Vegas, Nev., one presenter discussed a study that sought to answer that question for anabolic androgenic steroids (hormones that stimulate masculine physical characteristics) in young Thoroughbreds.

Currently there are four anabolic androgenic steroids commonly used therapeutically in racehorses: Stanozolol, nandrolone, testosterone, and boldenone, said presenter Benjamin C. Moeller, BS, a graduate student at the K.L. Maddy Equine Analytical Chemistry Laboratory at the University of California, Davis