Drug Positives And Environmental Contamination: The Skeptics’ Viewpoint

by | 03.21.2018 | 11:30am

It has been a tough couple of years for racing commissioners in Kentucky. Besides the recent last-minute rescinding of ractopamine positives against trainers Rusty Arnold and Joe Sharp, there was last year's void of three violations for dextrorphan. Then there's the ongoing methocarbamol case the Kentucky Horse Racing Commission faces with Graham Motion, who like Arnold, is widely thought of as a good guy with a pristine record. The phrase “environmental contamination” has been a well-worn one in all three cases, prompting commissioners to ask equine medical director Dr. Mary Scollay, ‘What are we going to do about this environmental contamination problem?'

Scollay – and others — say the question is more complicated than that.

For starters, it's difficult to define environmental contamination. For the purposes of the International Federation of Horseracing Authorities, it refers to the exposure of a horse to errant ingredients in hay or feed, as in the case of two show jumpers who tested positive for Sparteine last year while competing in Portugal. The antiarrhythmic agent is found in the plant Scotch broom, which was later discovered in the hay provided to the horses by the horse show organizers. The Federation Equestre Internationale (FEI) dismissed the findings. In such cases where a feed producer or hay producer has included a problematic ingredient before the substance reaches the barn, it isn't reasonable to assume the trainer would have any knowledge or control over the horse's exposure.

That definition doesn't seem to consider employees' hands, bedding, or stall walls as part of the environment. Scollay says that's because exposure from those surfaces can be limited or prevented. From the perspective of a regulator, she said, that's an important distinction.

“If you accept that that's environmental contamination, then you encourage trainers to proactively introduce substances into horses' environments, deliberately mismanage medications, and incentivize the hiring of substance abusers,” said Scollay.

The other problem with using “environmental contamination” as a catch-all to describe the presence of drugs in bedding, walls, (or in one research paper, cobwebs hanging from a barn ceiling) is that unlike the case of feed and hay the horse will certainly eat, it's hard to be sure how much of a drug a horse could or would ingest from flooring or walls.

There's certainly no question animals and humans are taking more medications than ever before in the United States, but Scollay says it's important to remember there's a lot of variance in the way drugs behave, both inside and outside the body. Some drugs take drastically longer to break down in a horse's body than others, even drugs within the same classification like anti-inflammatories (all dependent on the route of administration).

A 2017 study touted by the National Horsemen's Benevolent and Protective Association found various therapeutic and illicit drugs in receiving barn stalls, with some substances like cocaine and its metabolites showing up in multiple stalls.

For Dr. Dionne Benson, executive director for the Racing Medication and Testing Consortium, that information may be interesting but it's not necessarily a courtroom-ready defense against a positive test. For one thing, the study didn't quantify the concentration of substance per surface area of wall or grams of flooring material.

“What you can take away from it is that there are substances in the environment. There is no doubt about it,” Benson said. “We know, for example, that our labs can find picograms of a substance, which is great. But having a drug in the environment doesn't necessarily translate into it being in detectable concentrations in the horse. Most drugs that we dose, we dose in milligrams or grams. The minute you put a dose of that size into a horse, you're diluting it into approximately 54,500 milliliters of blood.”

Then there's the question of bioavailability – how much of a dose introduced to the horse's mouth can actually be broken down in the digestive tract and pumped through the system. Different drugs behave differently in this regard and bioavailability is unknown for many drugs.

It's also not clear how well some drugs could survive in the environment. Scollay pointed to an often-cited 2008 paper published in the Journal of Veterinary Pharmacology and Therapeutics in which researchers examined the environment of a Louisiana racetrack. While some common substances such as phenylbutazone, flunixin, naproxen, and caffeine were found in runoff water, flooring and rafter dust, other substances were missing. Very little furosemide was detected, which Scollay finds surprising, given how many horses receive it, and clenbuterol and acepromazine were not found at all. Very little phenylbutazone or naproxen were detected in runoff water, although they were found at varying levels in stall flooring, which may indicate those compounds don't hold together well in water.

For those skeptical of environmental contamination, the findings suggest some drugs would be better than others at holding together well enough to enter a horse's body and be metabolized in the same way as if they were administered intentionally.

Some people have wondered whether a horse could come up positive after eating hay or straw that had been urinated on by a horse who had received a drug. Benson believes the risk of this at a practical level is low – drug testing thresholds developed in academia are derived from horses who are also coming into contact with soiled bedding and flooring.

“I will tell you whenever we come up with a threshold we don't have magic horses or magic stall cleaners who come in and clean the stalls more often or better than they can be cleaned at a racetrack,” she said. “The best barns in the country do a better job than any research facility could because the grooms are on top of it. I don't know that that's really a relevant or applicable argument.”

But what about the flooring material beneath hay and straw? Some horsemen have noted the dirt floors underneath racehorses' stalls also contain drugs. The 2008 study in Louisiana found 251 nanograms of flunixin per gram of stall floor dirt in one ship-in stall. That may sound like a lot when a laboratory is testing at nanogram or picogram levels, but at that concentration Scollay says a horse would have to consume over 4,300 pounds of dirt to give itself the equivalent of the 500 milligrams contained in an oral dose of flunixin. As with any means of oral exposure to a drug, a horse could get a positive without consuming the equivalent of a full dose, but the smaller his exposure, the closer to the race it probably must happen to show up in a test.

Laboratory standards

One of the biggest reasons for discussing the role of environmental contamination at this point in regulatory history is testing laboratories. As technology becomes more advanced, labs can detect drugs in smaller concentrations in a horse's blood or urine. This has fueled fears about whether a spilled cup of coffee on a hay bale might now constitute a shed row's worth of caffeine positives.

Scollay agrees with environmental contamination proponents there needs to be a threshold established in each state as to what constitutes a positive and what doesn't, but not because she believes a horse is going to eat several pounds of dirt in its stall. Although testing contracts and testing laboratories have improved drastically in the past several years, disparities pose problems if a trainer orders a split sample be sent to a lab with different abilities and standards. Without clear guidelines on what's ‘positive' and what's not, most laboratories can only make a determination based on their ability to find a drug or not. That lack of uniformity can cause almost as many headaches as a disparity in testing quality itself.

Then there's a bit of ambiguity in the handling of some of those positives. Scollay points to the current ARCI model rule language, which allows regulators to take “mitigating circumstances” into account when considering penalties for owners and trainers. This phrasing was designed to allow regulators the chance to reduce or eliminate sanctions against trainers when there was evidence a drug exposure was outside their control or unintended. Because it also appears in penalty guidelines for owners however, there is an inconsistency as to whether a horse is disqualified, particularly for Class C drugs, many of which are therapeutics. For Scollay, that muddies the waters and further stokes the confusion surrounding blame for positive tests.

But what if we're wrong?

Because our understanding of how drugs behave in the environment is still evolving, there's always a chance some substances could turn out to be more potent than flunixin and a horse may not have to chow down on pounds of dirt to get a positive test as a result of accidental exposure.

The Equine Drug Research Council, an affiliate of the KHRC, began researching substances in stalls and bedding several months ago. The project is still in progress, but so far Scollay says the results do provide horsemen with a few guidelines they can use now.

“We detected a broad range of equine therapeutic medications, multiple human substances of abuse,” she said. “We have very few quantitative results yet; it was just a first pass to see what we could see. We're going to resample so we can actually talk about nanograms per square foot.

“In the screenings we did, we had many more findings on the walls than we did on the floor, which suggests substances are on people's hands, and not being introduced via [human] urine or passing through the horse. That says it can be prevented from being introduced to environment.”

Trainers shipping into the receiving barn can't control what may have taken place in a stall before their arrival, but Scollay suggests they can hang hay in a net instead of scattering it on the floor to reduce the horse's exposure to bedding and flooring. Horses approaching race time could be tied in their stall to limit contact with the walls (this is often done anyway as they are being groomed for their walk over). Employees could wear gloves when handling horses' mouths.

“There are more reasons to wear gloves than just to prevent the spread of drugs,” said Benson. “How many EHV-1 outbreaks have we had this year? [Wearing gloves is] simple biosecurity. It's so important for horse health. There's a whole host of benefits you derive by training your employees to wear gloves, and wearing different gloves with each horse.”

For Benson, a case of true environmental contamination usually involves a flurry of positives for a substance like glaucine or ractopamine, as was the case in 2014 when several British racehorses tested positive for morphine in what was later determined to be a case of poppy seeds ending up in their grain. In those cases, it's often possible to ask a feed company for batch samples to see whether those could be the culprit.

For Benson and Scollay, that means there's a lot of work ahead in terms of research and educating commissioners on what information is already available.

“This is certainly not the end,” Scollay said. “It's just a start. But I want people to start questioning when they hear ‘environmental contamination' and not say ‘Oh, yes!' but modulate that with, ‘Is it really a thing in this case?'”

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