The Straight Dope

Is post-event drug testing becoming too sensitive, netting too many innocent violators? Are drug withdrawal guidelines for therapeutic medications too unreliable to be useful? Or are policies and tests being fine-tuned in a sensible manner in order to weed out the cheaters and increase odds of a fair and level playing field? As with so many other controversial issues, the answer depends on whom you talk to...and whom you're talking about!

Withdrawal Times: Case in Point

One would guess that Thoroughbred racehorse owner Fred Bradley has a few frustrations concerning drug withdrawal guidelines: Last spring, prior to the $6-million Dubai World Cup race, he was given a two-page document listing allowable medications and their withdrawal times. Twenty-eight days before the race, Bradley's Thoroughbred, Brass Hat, was injected with methylprednisolone acetate, a corticosteroid used to treat inflammation that, according to the document, had a 23-day withdrawal time. But after Brass Hat finished second, earning a healthy $1.2 million, drug tests found trace amounts of the corticosteroid in the horse's urine sample, and the horse was disqualified.

Although these sort of problems are more dramatic and media-worthy when they involve high-stakes players, it's still hurtful and frustrating when the junior rider, the amateur adult, or owner of a racehorse that competes on regional circuits, has to return the ribbon, title, or purse because trace amounts of drugs showed up unexpectedly outside suggested withdrawal times.

Depending upon the sport, innocents can run afoul because of the jurisdiction (which test for different things and "call" different levels), the testing laboratory (different tests), the individual chemist running the test (experience), conditions in individual horses that affect metabolism of drugs, inadequate withdrawal guidelines, varying types of drug testing policies, or because owners/trainers/veterinarians just weren't careful enough.

Inconsistencies Hurt

To recap, show and racing authorities each have sets of rules that assign drugs into various categories, based on a drug's ability to affect performance and its therapeutic value.

The Association of Racing Commissioners International, Inc. (RCI), for example, classifies drugs and therapeutic medications into five different categories.

These classes range from prohibited stimulants and depressant drugs, which have the highest potential to affect performance and no generally accepted medical use (opiates, psychoactive drugs, amphetamines, etc.), down to therapeutic medications with little or no potential to affect performance within concentration limits (DMSO, anti-ulcer drugs, anticoagulants, etc.).

Thomas Tobin, MVB, PhD, Dipl. ABT, professor of veterinary science at the University of Kentucky's Gluck Equine Research Center, is a pharmacology expert, author on equine medication control, and an active participant in racehorse medication issues.

He says, "RCI Class 1 drugs are narcotics, stimulants, amphetamines, etc., none are therapeutic and all have considerable ability to influence performance. Class 2 drugs have less ability to influence performance; Class 2 therapeutic agents include local anesthetics used for diagnostic procedures, stitching up a horse, or minor surgeries. Class 3 therapeutic agents include bronchodilators such as clenbuterol, antihistamines, and tranquilizers such as acepromazine. Class 4 therapeutic medications include NSAIDs (non-steroidal anti-inflammatory drugs) and steroidal anti-inflammatories such as methylprednisolone. Class 5 drugs consists of substances such as DMSO and the anti-ulcer medications, which have little or no ability to affect performance."

Similarly, other show and sport organizations, including the United States Equestrian Federation (USEF), the American Quarter Horse Association (AQHA), the Fédération Equestre Internationale (FEI), the American Endurance Ride Conference (AERC), and so on designate three or more drug categories.

What's legal and what isn't varies among the organizations. Kent Allen, DVM, of Virginia Equine Imaging in Middleburg, Va., served as Veterinary Services Coordinator for the 1996 Olympic Games and was the highest-ranked veterinary official at the 1999 Pan American Games and the 2000 Olympic Games.

As FEI past vice chairman of the Veterinary Committee and current vice chairman of the Medication Advisory Group as well as USEF chair of the Veterinary and the Drug and Medication Committees, he's very familiar with the policies and complaints concerning drug testing.

"A lot of the drugs that people would try to cheat with on a racehorse would never be used on a performance horse and vice versa; there is no reason to," Allen explains. "People try to hop up and excite racehorses so they'll run faster, but that's the last thing you want to do in a show horse. So drugs like fluphenazine (a long-term tranquilizer) is not allowed under most racing jurisdictions or under USEF and FEI rules, but racing jurisdictions may not expend the cost at the lab level to detect this drug that USEF and FEI would because of the potential for abuse in jumpers and show horses. For example, in the USEF, isoxsuprine (a vasodilator used to treat problems associated with poor blood circulation in hooves, i.e., navicular or laminitis) is a permitted substance, meaning it's not likely to have a significant effect, so we don't regulate it. However, isoxsuprine isn't allowed by the FEI and most racing jurisdictions."

While the differences between what's permissible in racehorses vs. performance horses isn't likely to be an issue for most competitors and trainers, what does jam up the works are the geographic differences in drug regulations.

One of the most interesting conundrums is in U.S. horse racing, which has no national standard.

"There have been approaching 28 varying sets of rules in the U.S. because racing is a state matter," says Tobin. In other words, what's legal in Ohio might be illegal in Indiana. "The rules are characterized more by their diversity than by their commonality. Some jurisdictions may not 'call' low or trace concentrations; others will 'call' lower concentrations. Compliance becomes a problem for everyone--the veterinarian, the trainer, the owner."

On top of that, different tracks in different states send test samples to different laboratories--and testing labs and individual chemists do not necessarily employ identical means for drug detection.

"Most people think a drug test means putting a sample in a machine and the machine giving an answer," Tobin says. "But it depends on who's doing the testing and the testing performed. One chemist's testing can be a 100-fold more sensitive than someone else's. At what point the chemist loses track of a drug in the horse's system can depend entirely on how sensitive the detection test is, in lay terms, how 'high' (sensitive) the chemist cranks up the test."

Think of it as a matter of how many zeros the chemist chooses to look for.

Tobin explains, "Let's say a drug dose has a seven-hour half-life; in other words, half of the drug is excreted within seven hours. Three-quarters is excreted within 14 hours, 90% is excreted in one day, etc. Nevertheless, there still can be an enormous number of molecules left and detectable in the horse.

"Say, for example, you have this figure representing a full dose of the drug as a six followed by 20 zeros," says Tobin. "Day 1, one zero drops off; Day 2, another zero drops off; Day 3 another zero drops off, and so on. How long that drug will be detectable is partly determined by the chemist's threshold, where he's going to cut off the search for more zeros. If the drug has no allowable limits--zero tolerance--the chemist can test as far up and down that row of 20 zeros as his instrumentation will allow."

As a result, differences in a chemist's technique and test sensitivity can essentially invalidate recommended drug withdrawal times.

Likewise, the AERC uses different labs for drug testing, encountering the same disadvantages.

"When there is no standardization between testing laboratories as to which testing methodology can be used, laboratories can arbitrarily start using a more sensitive test," reiterates Trisha Dowling, DVM, Dipl. ACVIM, ACVCP, professor of veterinary clinical pharmacology at the Western College of Veterinary Medicine at the University of Saskatchewan in Saskatoon, Canada, and a member of the AERC and Equine Canada veterinary committees. "In effect, the testing laboratory decides how rigorous a 'no drug' policy will be when they select the testing method."

She notes that enzyme-linked immunosorbent assay (ELISA) tests can detect small amounts of drugs long after other methods would have yielded negative results.

"Unfortunately, veterinarians and riders are unlikely to know what screening test is being used and may not know that the screening test (and therefore the detection time) has been changed until notified of a drug violation," she adds.

Some groups, including the RCI, USEF, and AQHA, suggest or designate "thresholds" or restricted levels of medications for specific therapeutic drugs, offering guidelines that allow certain concentrations of particular therapeutic medications; regardless of who does the testing or what test is used, anything above a certain guideline level yields a positive result while an amount below guideline levels is considered a negative result.

Says Tobin: "With an established threshold, the chemist has to cut off the test at a certain point; that's a much more definitive situation."

Michael Bednarek, PhD, adjunct instructor of Western Horsemanship and Equine Reproduction at Cazenovia College in Cazenovia, N.Y., has exhibited at AQHA shows for 35 years. He is a member of the National Board of Directors and a carded judge for the of the National Snaffle Bit Association (NSBA), International Buckskin Horse Association, Palomino Horse Breeders of America, and Pony of the Americas Club. Bednarek describes how threshold recommendations work in the AQHA, which employs policies similar to other organizations that permit threshold levels:

"The AQHA allows the use of 12 therapeutic drugs within 24 hours of showing if administered within their dose recommendations to ensure compliance with their maximum plasma levels," says Bednarek. "There is a maximum amount of each drug that's allowed in the horse's system. Some of the allowed drugs are Banamine, a drug commonly given to colic sufferers for pain; Bute, for pain or inflammation; lidocaine, used for suture repair of skin lacerations; and ketoprofen (Anafen) and isoxsuprine, commonly used for pain in the navicular area. A medication report must be filed with show management if a horse is on any of these drugs, as there could still be some of the drug in their system even if it was given more than 24 hours prior to showing."

As for "zero tolerance" or "no drug" policies, that's another slippery slope in the unstandardized testing labs. For groups with zero tolerance polices, such as the AERC, no trace amounts of any drugs are permitted.

" 'No drug' rules sound nice, but are scientifically unreasonable," states Dowling. "At least in endurance, most violations are innocent mistakes. But with a 'no drug' rule, getting busted for Banamine is as bad as getting busted for cocaine! While there is no acceptable excuse for finding narcotics, amphetamines, or mood- altering drugs approved for human use only in the blood of competing horses, the occasional detection of trace levels of antihistamines, bronchodilators, or non-steroidal anti-inflammatory drugs is much more understandable."

Establishing permissible levels for specific therapeutic drugs is the sensible way to go, Dowling asserts. "While some people argue that it will be difficult to get a consensus on what concentration is 'pharmacologically significant' and performance-enhancing, it's done all the time for drugs used in food animals, where they set maximum residue limits and put withdrawal times on the drug's label," states Dowling. "If we can make such a decision when human food safety is at stake, I believe we can do it for horses. I'd like to adopt the racing system of five classifications of drugs and thresholds for the valid therapeutics (steroids, NSAIDs, bronchodilators, etc.)."

Uniform Rules

While those in endurance and racing struggle with inconsistencies, those who compete under USEF, AQHA, and FEI auspices enjoy much more uniformity--and thus dependability--in drug testing.

"The USEF is nationwide and, since 1995, owns and operates its own laboratory," says Allen. "It is the only federation in the world to do that. We will run about 15,000 samples through the lab this year--the largest sport horse lab in the world by a good margin. (In comparison, the FEI worldwide does about 2,500 samples.) We're also the laboratory for the AQHA, whose drug rule is very similar to ours, and we are of one of the four FEI worldwide laboratories."

Because all USEF and AQHA tests are conducted in one lab, everyone is on a level playing field--same tests, methodology, expectations.

Like the RCI, the USEF, AQHA, and FEI have guidelines that classify drugs as forbidden (performance-enhancing drugs of which many, but not all, have no commonly accepted veterinary use), restricted (likely to be performance-enhancing, but also commonly used in therapeutic medication), and permitted (no significant performance enhancement, has therapeutic value).

"It's a pretty comfortable fit," Allen says.

Under USEF rules, forbidden drugs include those with ingredients that contain stimulants, depressants, tranquilizers, psychotropics, and local anesthetics, even though the medication itself might be legitimately useful for treating equine disorders or conditions.

"Everybody knows Ace," says Allen. "If you want to trailer or clip your horse prior to the show, you want to use acepromazine. But you'd better use it a long time prior to show, because it can last in the horse up to 86 hours.

"The problem with Ace is, how do you differentiate on a drug test between that use and the person who, a half-hour before the show, gave a little bit of Ace to calm their horse down."

He explains, "The problem is that a large amount of Ace given a long time ago, and a small amount of Ace given very close in, look pretty much the same. So there's not always an easy answer."

A competitor can use restricted drugs under USEF rules, as long as administration amounts and timing of the drug present in blood or urine are below a certain level at the time of show.

"Examples include all the NSAIDs permitted for use in the horse (Bute, Banamine, Arquel, ketoprofen, Naprosyn, etc.), the muscle relaxant Robaxin, and the most commonly used corticosteroid in horses, dexamethasone,"Allen says.

Acceptable USEF drugs include all antibiotics with the exception of procaine penicillin G (because testing can't differentiate the procaine in this from procaine given to reduce pain), antiprotozoals, anthelmintics (dewormers), anti-ulcer medications, and Regumate.

Getting Caught

Even under the most stable of situations, innocent competitors can still get into trouble, even when they follow the guidelines concerning detection/withdrawal times, dosage amounts, etc., due to individual circumstances that affect how quickly or completely a drug exits the body.

"The veterinarian, trainer, or person responsible for that horse still has to factor in aspects of that particular horse's life," warns Allen. "Is he slightly dehydrated, which could make drug levels higher than normal?"

Some racing jurisdictions recognize this, Tobin says. "Sanctions for small 'overages' of common therapeutic medications are modest, and the record may expunge at the end of the year," he explains.

Orally administrated drugs or repeated or long-term administration of some drugs can delay or extend the time it takes for a drug to leave the body.

So can a meal fed about the time of oral administration of the drug, as well as individual variations between animals such as amount of body fat, breed, gender, health, and stress.

"Dose amount is usually important," Tobin states. "If you're putting gram doses in the horse, the chemist is going to trip over it. If you're putting microgram doses in, the chemist will have to hunt for the drug."

For many show and race competitors, however, the question still remains: Are drug testing policies being developed and used in a manner that's unfair or unreasonable against people who are just trying to medicate their horses?

"The answer is 'No'," states Allen. "Technology is progressing across the board, whether it's phone service, computers, digital radiographs for horses, or drug testing for horses. Even with changing technology and increased sensitivity in drug testing, the reality is there is an agreed-upon level for which a tester looks for a drug. That doesn't mean a chemist is going to chase the drug down lower; he's going to keep it where he's always been looking at, it's just a different technology to detect it.

"If organizations changed the technology on detecting medications or changed drug testing sensitivity dramatically and then didn't tell anybody, it would be a tremendous abuse of the system," adds Allen. "But that's not the case."

The USEF will almost always make known significant changes in drug testing or classifications to their members prior to implementing those changes.

"Don't get too sucked into the 'innocents' and the labs, because they're usually not so innocent, and the labs aren't working in a vacuum on their own," Allen notes. "The labs are running tests based upon what the regulatory agencies are telling them is appropriate for their kind of horse and what is common knowledge within the industry as to what should and shouldn't be done."

Still, Allen admits, it's easier for competitors to comply when one set of rules are applied nationally and uniformly, and when all tests go to the same lab.

"When there are a lot of different jurisdictions and different laboratories running different tests, it does make compliance more difficult," he says.

Take-Home Message

Although many might disagree, the bottom line, says Tobin, is there are never guarantees.

"The only sure way to comply (with drug rules) is don't give any drugs, ever," he says. "If you're in situation where you're treating a horse with a medication, sooner or later, you're going to get in trouble."


For detailed information concerning drug threshold levels, factors affecting drug withdrawal times, therapeutic medications, etc., check out the document "National Horsemen's Benevolent & Protective Association, Inc. Proposed National Policy on Drug Testing and Therapeutic Medicine" at This document was published by, and is also available in, the January 2003 issue of the Journal of Equine Veterinary Science (Volume 23, Number 100).

For more information on the FEI Medicine Box, visit --Marcia King


This past spring, Fédération Equestre Internationale (FEI) officials met in London and Paris to develop better information on medications and to implement changes that provide more consistency in drug testing.

"We have been gathering very good withdrawal and detection information on a group of 16 drugs that we call the 'Medicine Box,' " explains Kent Allen, FEI vice chairman of the Medication Advisory Group Committee and United States Equestrian Federation chair of the Veterinary and the Drug and Medication Committees.

"These are therapeutic medications commonly used throughout the world," Allen says. "This information will be disseminated out through the horse press and through the veterinary outlet so everyone will have good information as to when they can withdraw a particular drug from a particular horse. Then, factoring in the aspects of that particular horse's life, you'll have a withdrawal time frame from which the drug was given to the time you would then show the horse, and have confidence that the drug would not be in the system."

Information on five of the "Medicine Box" drugs was released on July 1; information on the 11 remaining drugs is expected to be released later in 2006, with information available at the FEI web site (

"We're going to expand this process slowly into an ever larger group of medications and drugs," says Allen.

In concert, the FEI is standardizing its four drug testing laboratories. "Part of the difficulty in the past was there were a bunch of labs, and they've been winnowed down now to just a few, all with very good capabilities," Allen reports. "They've gradually started working together more and more via the auspices of the FEI Veterinary Committee, FEI Legal Committee, and FEI Medication and Advisory Group."

Furthermore, this year the FEI will permit competitors to collect and send a urine sample into an FEI or USEF lab prior to competition to see if therapeutic drugs are still present. "For example, a veterinarian might have given a horse acepromazine a week ago and wants to know if it's still present, because they don't want to show the horse if it is. No one has ever had the ability to do that before."--Marcia King

About the Author

Marcia King

Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.

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