Rarity on the Racetrack:
Intentional Medication Abuse in Horse Racing is Infrequent

Dr. Thomas Tobin, Dr. J. Daniel Harkins & Dr. George D. Mundy

Administration of prohibited medication is a lot less common on the racetrack than you might think. In fact, intentional medication abuse in the racing industry is extremely rare, according to studies by prominent veterinary researchers.

"Horse racing actually has much more stringent and effective control of medication abuse than other sport organizations such as the NCAA, NFL and NBA," says Dr. Thomas Tobin from the Gluck Equine Research Center at the University of Kentucky in Lexington.

Testing has become increasingly accurate and precise; capable of detecting minute amounts of substances over a long period of time. Racing chemists are able to measure substances on a parts per billion (ppb) basis, thus exposing performance-altering substances as well as legal, therapeutic medications.

"To realize the size of ppb," Dr. George Mundy of the Kentucky Racing Commission explains, "consider the following example: If you are 32 years old, you have lived about one billion seconds. Close your eyes for one second — that is one ppb!"

To help distinguish between performance-affecting agents and substances with no affect on a race, the industry has classified over 500 medications with regard to their impact on a horse's race performance. The Association of Racing Commissioners International (ARCI) classification, which is followed by most racing states, divides medications into the following categories:

Class 1
These are hard-core illegal narcotic opiates and stimulants with no place in racing. They also have the highest abuse potential. Substances in this class can have a profound affect on a horse's performance. Examples include morphine, etorphine and cocaine.

Class 2
This class has less abuse potential, but still includes illegal substances. Some agents in this class have legitimate therapeutic uses for horses in training. Examples include local anesthetics, caffeine and barbiturates.

Class 3
Legitimate therapeutic agents with the potential to affect performance are included in this class. Examples of these substances are antihistamines, bronchodilators and tranquilizers.

Class 4
These substances are legitimate and widely used therapeutic agents. Theyinclude phenylbutazone, corticosteroids and isoxsuprine.

Class 5
This class has negligible effects, if any. Examples are dimethyl sulfoxide(DMSO) and polyethylene glycol (PEG).

With the high technology and increased accuracy of urine testing, horsemen might assume more medication abuse would be disclosed; but quite the contrary. Increased technology has actually revealed racing as a clean, upstanding industry. The American Association of Equine Practitioners (AAEP) has identified about 50 substances that are legitimate therapeutic medications (Class 3, 4 and 5) for horses in training. According to Dr. Tobin, traces of these therapeutic medications are the most common chemical identifications and eight of these agents give rise to about 50 percent of the reported medication infractions in some jurisdictions.

A study in Kentucky was conducted from 1992 to 1994 and analyzed data of 21,599 urine samples from Thoroughbreds, Standardbreds and Quarter Horses in that state. As part of ARCI's Quality Assurance Program, six chemicals were intentionally run through as blind samples containing Class 1, 2 or 3 substances.

Not including the six blind samples, 28 substances from Class 1, 2 or 3 were identified. This means that only 0.1 percent of all samples resulted in violations. None of these events involved ARCI Class 1 substances, which are those with the greatest potential to affect the performance of a racehorse. Only one was a Class 2 substance; mepivacaine. This chemical is approved by the Food and Drug Administration for use in horses as a diagnostic and therapeutic nerve block, epidural (spinal cord) anesthesia, intra-articular anesthesia and topical application; mepivacaine is therefore a legitimate therapeutic medication.

All remaining chemical identifications involved ARCI Class 3 medications. Notably, 15 samples with procaine were descried. A metabolite of pyrilamine was detected in five samples and phenylpropanolamine (PPA) was identified in three specimens. Acepromazine, atropine, clenbuterol and promazine, all legal therapeutics, were identified in one sample each, accounting for the remaining four chemical identifications.

"These [identifications] are all legitimate therapeutic medications and it is highly probable that a very large proportion of these identifications represent minute residues of legitimate therapeutic medications," comments Dr. Tobin.

The Prevalence of Procaine Identifications
Procaine, an ARCI Class 3 substance, is the most commonly detected pharmaceutical in post-race urine samples. Though a legal therapeutic, traces of procaine residues in post-race samples can pose a major problem for horsemen.

"Legal administration of procaine involves the therapeutic preparation of procaine penicillin and is present in some medicated animal feeds," says Dr. Mundy. "It therefore can be present through legitimate therapeutic medications of racehorses or inadvertent feed contamination."

Procaine is a highly efficacious and inexpensive broad spectrum antibiotic that is easily administered intramuscularly. However, therapeutic procaine penicillin treatments can cause traces of procaine to appear in post-race urine samples for up to one month after administration.

In post-race analysis of urine, it is impossible to distinguish between legitimate therapeutic use of procaine penicillin and other uses of this agent. Procaine is abused when administered as a local anesthetic or when used as a nerve or joint block, though it is weak and slow to onset.

According to studies by Dr. J. Daniel Harkins of the Gluck Equine Research Center at the University of Kentucky in Lexington, 73 identifications have been made for procaine in North American racing in the last two and a half years. Many of these identifications have most likely resulted from the legitimate therapeutic administration of procaine penicillin and simply represent detection of pharmocologically insignificant traces of this agent.

So how can testers tell the difference between proper and improper administration of procaine? The study by Dr. Harkins determined the minimal dose of procaine that causes pharmacological effects is unlikely to have been associated with a significant local anesthetic effect af procaine at the time of racing, thus not affecting the outcome of the race. This amount is also known as the highest no-effect dose (HNED). Once this level is established, a plasma/urinary threshold can be used to establish a "No-Effect Threshold" (NET) for procaine. These levels are determined in order to prevent administrative action on horsemen who have given legitimate, therapeutic medication to their horses.

"Olympic athletes can take ibuprofen the night before a race, compete and receive gold medals without fear of receiving fines or suspensions," Dr. Mundy explains. "The thresholds researchers set will allow veterinarians and trainers to use legitimate therapeutic medications without running the risk or alienating owners, trainers or future horse industry participants."

Currently, the proposed NET for procaine is 25 ppb in urine. The study determined that the HNED of procaine is 5.0 mg, a surprisingly small amount according to Dr. Harkins.

"Administration of this dose to horses showed that the peak urinary concentration of procaine is about 25 ppb," Dr. Harkins comments. "Since this concentration of procaine in equine urine is unlikely to be associated with a pharmacological effect, there is no need for administrative action based on identifications of concentration of procaine in equine urine of less than 25 ppb, the established 'No-Effect Threshold'."

Because chemical testing has become increasingly accurate and precise, the industry has confidence in the reports that chemical abuse is rare in horse racing. However, this increased sensitivity has caused secondary problems, such as identifying unintentional therapeutic traces, thus initiating unnecessary administrative action. Once we are aware of causes to inadvertent chemical identifications, legitimate therapeutic treatments will not be condemned.

Dr. Thomas Tobin is a professor of veterinary science and toxicology at the University of Kentucky's Gluck Equine Research Center in Lexington. He is a veterinarian, pharmacologist and toxicologist. He graduated from University College, Dublin in veterinary medicine, and holds a PhD in pharmacology and toxicology from the University of Toronto. Since 1975, Dr. Tobin has directed the Equine Pharmacology and Experimental Therapeutic Program at the University of Kentucky. He is the author of Drugs and the Performance Horse and about 300 other research publications. The current thrust of his research is on developing 'No Effect Thresholds' for therapeutic medications.

Dr. J. Daniel Harkins is a research specialist at the University of Kentucky's Gluck Equine Research Center in Lexington. Upon graduating from Purdue University with a DVM, Dr. Harkins owned a mixed animal practice in northern California. He then went back to school, to Louisiana State University, to receive a graduate degree in equine exercise physiology. After researching at Cornell University in equine sports medicine, Dr. Harkins accepted his current position at UK.

Dr. George D. Mundy received his DVM degree from the Ontario Veterinary College, at the University of Guelph in Ontario, Canada. After graduation, he practiced as associate resident veterinarian for two prominent horse farms in Canada and Kentucky. In 1990, Dr. Mundy joined the Kentucky Racing Commission. In 1997, he left that position to join Hill n' Dale Farm near Lexington, Kentucky, as Resident Veterinarian and General Manager. He also served as Veterinary Consultant to Breeders' Cup Limited, heading up the veterinary inspection panel that monitors participating horses on Breeders' Cup Championship Day, the Kentucky Derby and the Preakness Stakes.