The Steroid Debate

"Steroid" use has made headlines because of abuse in human athletes for the past decade, from Major League Baseball to track and field events. The topic has also become hot in the horse industry, from steroid use for bulking up young horses in sales, to attempting to enhance performance of show horses and racehorses. However, not all steroids are the same, and there is widespread misunderstanding about what the differences are between corticosteroid and anabolic steroids.

Corticosteroids and anabolic steroids are not the same. (For more on anabolic steroids and corticosteroids see the sidebar below from

Corticosteroids are a class of steroid hormones produced in the adrenal cortex, explained Wayne McIlwraith, BVSc, PhD, FRCVS, DSc, DrMedVet (hc), Dipl. ACVS, Barbara Cox Anthony University Chair and Professor and Director of Orthopaedic Research at Colorado State University (CSU). They are involved in wide range of physiologic systems in the body, such as stress and immune response, regulation of inflammation, and protein catabolism (breaking down of molecules). Their main therapeutic use in horses is to combat inflammation.

"The corticosteroids are divided into glucocorticoids and and mineralocorticoids," he explained, adding that the ones used for therapeutic purposes in horses are the glucocorticoids. Among common glucocorticoids used in horses for intra-articular joint injections are betamethasone esters (Celestone), triamcinolone (triamcinolone acetonide, or Vetalog), and methylprednisolone (methylprednisolone acetate, Depo-Medrol). The most common corticosteroid used systemically is dexamethasone.

Corticosteroids are used for allergic reactions (such as hives), shock, and intra-articular treatment to combat inflammation from traumatic joint disease, according to McIlwraith. "They are more than pain killers," he said.

"Historically, intra-articular corticosteroid use has been reputed to cause harm, but more recent research at CSU has demonstrated beneficial effects without any harmful effects of betamethasone and triamcinolone, whereas methylprednisolone does cause cartilage damage and is not recommended," he stated.

Anabolic steroids are a class of steroid hormones related to the hormone testosterone. They increase protein synthesis in cells, which results in anabolism (build-up of tissue), especially in muscles. "So anabolic steroids have androgenic properties (promote masculine characteristics)," said McIlwraith. "Anabolic steroids are used therapeutically to stimulate growth and appetite and treat chronic wasting conditions."

McIlwraith added that because anabolic steroids produce an increase in muscle mass and physical strength, they have been used in sport and body building to enhance physique. "However, it has been recognized in humans that their long-term use at high doses is associated with serious health risks," he stated.

Historically, anabolic steroids have been used in equine veterinary medicine for treating horses that are not doing well and have relatively low body mass or strength, explained McIlwraith. "In this regard, anabolic steroids have been classified as therapeutic. They also have been commonly used in geldings, whether they need it or not. (Some people) castrate a horse and then give it steroids."

Therapeutically, anabolic steroids are useful for the poor-doing horse. "Generally, unlike in humans, in horses they are not used for sustained periods, so they do not (cause) serious side effects," said McIlwraith. However, he cautioned, anabolic steroids "should not be used in performance horses because of potential performance-enhancing effects."

The debate in the racing industry currently concerns prohibiting and screening for anabolic steroids. At this point some discussion revolves around banning and testing for four specific anabolic steroids; some research experts in human medicine, as well as equine leaders, have supported the industry ban of all anabolic steroids. McIlwraith agrees with the total anabolic steroid ban in active performance horses.

Testing to find anabolic steroids has been ongoing in human athletes for years; testing in horses is getting better. "One of the problems the horse industry has on testing is how good is our testing," said McIlwraith. He agreed with authorities who have tested human athletes, in that once you start prosecuting for anabolic steroid use, "you better be able to deal with lawyers; you better be ready to defend your results."

Current racehorse steroid screening involves a urine test, but scientists are developing a blood test for anabolic steroids. McIlwraith feels the advantage of a blood test is that you can do "spot screening." Currently, he said, horses in the United States only get tested when they race, and they only have a urine sample taken.

However, McIlwraith also has clients around the world, and he said, for example, in France, the racing authorities can test racehorses at any time, whether they have just competed in a race or are just in training. Since blood tests are much easier to take than waiting for a urine sample, it's easier to take blood samples for random testing. And if someone is training on anabolic steroids, there are penalties.

In the U.S. racing industry there are more than 20 different laboratories conducting drug testing--mostly on the state level--and it is well-known that each lab does not test in the same manner. McIlwraith noted that other countries have federal testing laboratories for racehorses.

"We need to identify how best to drug test," he said. "That might be one or two labs for (the) whole country. Where's the expertise?"

The racing industry dispute over anabolic steroids pertains to regulation and testing--it's not that anyone believes these drugs should be used in racehorses.

"Testing for anabolic steroids in equine urine has been effectively used internationally for decades, and the Racing Medication and Testing Consortium model rule for urine recognizes that reality," said Rick Arthur, DVM, equine medical director for the California Horse Racing Board, and owner of a racetrack veterinary practice for 30 years. "Most racing chemists are convinced testing in blood will offer clear advantages. A number of labs are involved in research in this area and a few states are already officially testing for anabolic steroids in blood. A national policy could be proposed before the end of the year."

McIlwraith added, "There are tests for corticosteroids, and they are well-established and sophisticated. Corticosteriods have a number of beneficial indications. Nobody should be trying to take away the ability to use them. Generally these therapeutic medications have thresholds below which they (the testing labs) don't call it (as a positive). If you give an intra-articular corticosteroid a week before a race, the horse won't be called as testing positive ... it shows up, but they (the labs) don't call it below a certain level (a threshold that has been established and publicized).

"On the other hand, if you go in France, or England, or Hong Kong, they have lower thresholds (for corticosteroids)," noted McIlwraith. There have been well-publicized cases where horses tested positive for a corticosteroid used therapeutically in a joint.

However, there is no overlap in the tests for anabolic steroids and corticosteroids, McIlwraith said. "No one is going to pick up a corticosteroid when testing for anabolic steroids," he clarified. "They have different tests."

Take-Home Message

It is important that horse owners recognize that anabolic steroids and corticosteroids are not the same thing. Both have uses in horses with physical problems, but the use of anabolic steroids in performance horses is coming under the microscope as it has in human athletes. Testing is available for both of these, but the tests do not overlap in their results; in other words, if a laboratory is testing for an anabolic steroid, then it will not pick up a corticosteroid.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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