Clenbuterol Q&A With Dr. Rick Arthur


Rick ArthurHorsephotos


The tide is turning on clenbuterol. Within the past month, regulators and racetracks nationwide have announced new initiatives to quell its abuse. New prohibitions are in the pipeline for the New York State Gaming Commission, the Maryland Racing Commission, Gulfstream Park, Oaklawn Park and an alliance of Mid-Atlantic racetracks.

On May 1, the Canadian Pari-Mutuel Agency started banning clenbuterol 28 days out from race day at tracks country-wide. The California Horse Racing Board (CHRB) took action four months before that, enacting a years-in-the making, zero-tolerance clenbuterol clampdown that began New Year's Day 2020.

Drawing upon 10 1/2 months of perspective so far, TDN wanted to hear from Rick Arthur, DVM, the CHRB's equine medical director, to find out what California regulators and racetrackers have learned since the ban went into effect. Arthur fielded questions during a Nov. 17 phone interview, and an edited transcript of the conversations follows.

TDN: Please open with a condensed history of clenbuterol's rise in California from a bronchodilator to treat equine airway disease to a widely abused drug known to mimic the muscle-building properties of anabolic steroids.

RA: It is a very effective drug for lower airway disease. It is, I think, one of the better drugs I saw introduced during my years of practice. It just wasn't being used for small airway disease in some of the stables that we saw.

Shortly after the ban on anabolic steroids [by the CHRB in 2008] we started seeing an increase in the use of clenbuterol, primarily in Quarter Horses, but also in Thoroughbreds. In fact, in out-of-competition testing [OOC] we found 58% of Thoroughbreds and 100% of Quarter Horses had clenbuterol in blood tests. It became clear that it was an issue, and there were trainers who were very adept at using a lot of clenbuterol and still being able to get below the threshold level, which at the time was 5ng/ml in urine, which is fairly high.

Finally, the Quarter Horse industry came to us and said we need to do something about this. And what we did was eliminated the authorization for clenbuterol. And then some Thoroughbred trainers shortly thereafter asked us to do the same thing, which we did [in 2012]. So what happens is, if one guy is using clenbuterol, everybody has to use it, right? It does have a partitioning effect [that promotes lean muscle mass].

So what we did is we eliminated the authorization for clenbuterol. At the time our detection time was roughly between 14 and 21 days. And for the most part that worked fairly well. But what we saw in Quarter Horse racing is there were still certain trainers that were still able to find ways to use clenbuterol to their advantage.

The CHRB adopted the Racing Medication and Testing Consortium [RMTC]'s 140pg/ml threshold in blood in October 2014. In 2015, Quarter Horses reverted back to no authorized level-no threshold. And then that Quarter Horse regulation for clenbuterol became effective for Thoroughbreds on Jan. 1, 2020.

   TDN: And what is the plain-language explanation of CHRB Rule 1866.1? (Read the full version here).

   RA: Any horse who is treated with clenbuterol goes on the vet's list. That horse stays on the vet's list until it tests negative for clenbuterol in both blood and urine after working out. Even though it doesn't have a specific stand-down [time frame], it is very hard to get a horse of the vet's list that's been treated with clenbuterol within 30 days. Most of them [stay on the list] quite a bit longer, just as a practical matter. But that's how the rule reads: To prescribe clenbuterol, you have to have [an appropriate respiratory] diagnosis. You have to report the dosage. You can't have a prescription that goes for over 30 days.

   TDN: What has the CHRB learned about clenbuterol since the new rule went into effect?

   RA: Most practicing veterinarians say that even though they miss the drug, they have not seen very many negative effects. And we [as regulators] certainly have not seen any negative effects so far this year from not having clenbuterol. They can still use it if really needed, but the restrictions make it difficult to use with an actively racing horse.

I'm sure there would be some trainers who would like to use clenbuterol, in terms of horses, particularly, that aren't receiving Lasix. Those horses would be treated after their races. But we haven't seen that. We monitor this with [OOC] hair testing, and when we see clenbuterol in hair, we require the trainer to show us a prescription for that drug in our OOC regulations. In fact, all of the horses [this year] that have tested for clenbuterol in hair have been treated outside of California. That number would probably be a dozen, roughly.

We still see clenbuterol prescribed occasionally. It's still being used, but we don't see it in blanket use that we saw previously. Those horses are on the vet's list, and I don't think any of them started within 30 days of being treated with clenbuterol.

TDN: As you watch other jurisdictions crafting clenbuterol rules, what advice would you have for those regulators or for racetrack officials considering in-house policies?

RA: I think testing the horse to be clear of clenbuterol is key. From our experience with the drug, which is pretty extensive, trying to set a withdrawal time-like 30 days, which some jurisdictions are talking about-is not adequate. There's enormous individual variation with this drug, and I think that before a horse is allowed to enter, they should prove that they have no clenbuterol in their system with a urine test.

TDN: Regulators are always involved in a cat-and-mouse chase with dopers who are one step ahead of the rules. Now that the window of abuse on clenbuterol is closing, what under-the-radar performance-enhancing substance or practice is likely to surface next?

RA: It's not really under the radar. We are concerned with SARMs [selective androgen receptor modulators]. Those are a class of drugs that have anabolic-like activity, but they are not really anabolic steroids. We've seen some of them in testing already. The RMTC has recommended that a number of those be classified as serious violations. So that is a group of drugs that I think that we have to pay attention to.

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