Steroids Side Effects in Racehorses are Temporary and Reversible

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The World Anti-Doping Agency (WADA) essentially has a zero tolerance policy for the use of anabolic steroids in human athletes. An athlete could theoretically apply for a therapeutic use exemption (TUE) and receive permission to use anabolic steroids since several steroids have legitimate medical uses. However, it is unclear how often WADA grants such TUEs. Equine athletes have it much easier than their human counterparts when it comes to the freedom to use anabolic steroids.

The Racing Medication and Testing Consortium has approved the therapeutic use of four anabolic steroids in equine athletes. The therapeutic use of stanozolol (Winstrol), boldenone (Equipoise), nandrolone (Deca Durabolin) and testosterone are permitted for racehorses in many states that sanction horseracing as long as they are discontinued within a certain window prior to competition and test below a certain threshold level during in-competition testing.

Dr. Scot Waterman, executive director of the Racing Medication and Testing Consortium, explains the accepted uses of anabolic steroids in racehorses:

Question: We hear a lot about steroid use in human athletes. Are steroids used in racehorses?

Dr. Waterman: First, it is important to understand that there are two distinct types of steroids. Corticosteroids (prednisone, dexamethasone, etc.) are generally used to relieve inflammation. They are commonly used to treat inflammation in joints and in the airways of racehorses. The second type of steroids is anabolic steroids. They are used primarily by veterinarians to keep horses eating and training aggressively. They also are used to replace hormones lost in male horses after being castrated.

Question: Are racehorses permitted to race while being given either type of steroids?

Dr. Waterman: Generally, horses are not allowed to receive either type of steroids within 24 hours of a race. One exception is in Florida, where horses can receive prednisolone (a corticosteroid) on the day of the race. RMTC’s model rule on anabolic steroids, which eliminates those medications from racing competition, has been adopted or is in the process of being adopted in every major racing state (representing approximately 99.98% of the total Thoroughbred parimutuel handle in 2009).

The effect of various anabolic steroids and its negative impact on fertility has arguably been researched to a greater extent in horses than in humans. Stallion fertility specialists are very familiar with the anabolic steroid-induced suppression of natural testosterone products, testicular atrophy and decreased sperm count. Most experts acknowledge that the negative effects of anabolic steroids are temporary and reversible with no long-term or permanent problems.

Terry Blanchard, D.V.M., M.S. of Texas A&M University provides a straightforward and dispassionate explanation of the effects of anabolic steroids on fertility  in horses in an article published by Thoroughbred Times:

“There’s no doubt that if you give anabolic steroids at frequent enough intervals or at high enough doses, it does lead to testicular atrophy due to degeneration,” Blanchard said. “There have been very few long-term studies, but short-term studies, including ours, showed that treatment for three months causes considerable regression in testes size, decreased sperm production, and Leydig’s cells atrophy of the testes. Leydig’s cells are the cells that produce testosterone.

“We certainly have evaluated young stallions off the track that have testes too small to pass the breeding soundness examination, have confirmed with the trainer that the horses were getting anabolic steroids, and I’ve seen some of those horses, remarkably, within three or four months achieve enough testicular growth to pass a breeding soundness examination and go on to do very well their first year at stud. But, it takes a few months.

“So,” Blanchard continued, “if a horse races all the way through the fall of the year on anabolic steroids and then he only has a couple months before he comes off the steroids and goes into service, he may be a little behind the eight ball. But, nobody that I’m aware of has proven that there are long-term, permanent effects with anabolic steroids.”

The effects of anabolic steroids on human fertility and stallion fertility is similar. In both cases, exogenous steroid administration causes the suppression of natural testosterone production. Experts on steroid use in racehorses tend to describe these steroid side effects as “temporary” and “reversible” with no “long-term” or “permanent effects” from the use of anabolic steroids. Yet, experts on steroid use in humans tend to describe the steroid side effects in much more dismal and depressing terms.


Photo credit: Paolo Camera / flickr

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