Can diet cause a horse to fail a dope test?

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By Dr Derek Cuddeford

The Fédération Equestre Internationale (FEI) based in Lausanne lists on thirty A4 pages in PDF format substances that are prohibited in equines! In April 2013 there was a major scandal in Newmarket when it was discovered that horses from a prominent yard had failed a dope test. In this case, the agent discovered was stanozolol, a banned anabolic steroid which had been purposefully administered to the horses. In the United Arab Emirates (UAE) endurance horses have figured in 33 FEI Tribunal doping hearings in just one year and several animals have died during the winter season of endurance racing. Thus doping is a major issue in horse sports and also, a recurring issue amongst human sporting activities such as the Tour de France. In most of these cases, it is the deliberate administration of substances that results in a positive test. If a prohibited substance is of dietary origin it may lead to a case of involuntary doping and a positive test. However, it is impossible to discriminate between these two types of doping as the result is the same, disqualification and possibly banning from the sport. It is because of this that all people who ride competitively must be aware that their horse’s diet could be a source of prohibited substances.

The British Equestrian Trade Association (BETA) has introduced two assurance schemes designed to reduce the risk of naturally occurring prohibited substances (NOPS) being present in the manufactured feeds and supplements that may be fed to horses. Horses may be fed forages together with compound feed or straights such as oats or, a combination of the latter two. The Universal Feed Assurance Scheme (UFAS) and NOPS are designed for manufacturers of compound feeds. The Feed materials Assurance Scheme (FEMAS) together with the NOPS code are schemes designed both for raw material and straights providers. Thus, it is important that people in charge of purchasing horse feed only use feed materials from accredited suppliers; the respective logos will be stamped on bags or containers of horse feed or supplement. Accredited feed companies are subject to regular audit by the unbiased Agricultural Industries Confederation (AIC) to ensure they conform to the requirements of both UFAS and FEMAS. In this way, the risk of NOPS being an issue is much reduced or eliminated provided you buy products from suppliers who belong to these assurance schemes.

As with everything, there has been considerable progress over the years in the development of equipment capable of measuring prohibited substances. Whereas in times past the concentration of a substance in blood, urine, feed, etc could only be measured in terms of milligrams/100g sensitivities of equipment have increased so much  that microgram quantities can be measured and in some cases even nanogram amounts are now measurable. This is a minute amount equivalent to one part per billion! This means that great care has to be taken in feed preparation to avoid the presence of NOPS in a product; spilling a cup of coffee in the wrong place or losing a piece of chocolate could result in a positive dope test for caffeine and/or theobromine.

NOPS have been defined as “any substance that can exert an effect on a horse” and thus, this is an all-embracing definition!! The most common NOPS are caffeine, theobromine, morphine, nicotine, hordenine, hyoscine, theophylline and atropine. The first three are the most commonly found in feed either naturally present or as a result of contamination prior to manufacture. Good quality control using laboratory procedures to screen raw materials prior to manufacturing and to check for the presence of NOPS should result in the production of NOPS-free products.

Natural products and herbal preparations may represent a risk since they could result in a positive test outcome. Many do not come with an exhaustive analysis and one never fully knows what these products contain. Plants, as most people know, are a valuable source of some common drugs. These phytochemicals are currently attracting a lot of research effort to evaluate their effectiveness in different situations. Some are claimed to have a calming effect in horses such as the herb Valerian; this is not surprising since Valium (Diazepam) is extracted from Valerian roots and is used to calm nervous and/or anxious persons. In contrast, there are other herbs that claim to stimulate activity. The inclusion of materials that have calming or stimulatory actions violates FEI rules.

The FEI categorises regulated substances into either Banned Substances or Controlled Medication Substances. The former substances should never be found in any competitive horse at any time or level. The latter refer to substances that are commonly used and/or recognised as having significant therapeutic activity. The FEI regulations define threshold levels for these substances because they recognise  that many substances can produce a positive result but are present in minuscule amounts as a result of appropriate veterinary treatment, a certain diet or are produced by the horse itself. A good example of the latter is the endogenous production of testosterone in male athletes. High levels suggest drug usage but some men have naturally very high basal levels of the hormone and thus for these individuals the allowable threshold must be higher.

There are a number of ways that horse feed may become contaminated with prohibited substances. A problem may occur when raw materials are sourced from overseas where herbicide usage is not so intensive as in the UK. It is not unusual to see poppies growing on wastelands in the UK but they are rarely seen growing in agricultural crops. Imported feed materials, particularly from less developed countries, should always be screened for the presence of poppy seeds since they represent a source of opium. The latter contains about 12% morphine, used to produce heroin, as well as codeine, an effective pain killer. Poppies represent one of the best examples of a plant that can produce powerful phytochemicals for human usage and a failed dope test. Also, horse food should be purchased from manufacturers who have a feed mill which is dedicated solely to this purpose otherwise there is a distinct risk of cross contamination from other animal products that may contain banned substances. Feedstuffs that are based on sprouted cereals such as Brewer’s Grains, Distiller’s Grains, etc could be a source of hordenine and although these feeds are very useful in horse diets it might be as well to make sure that they are not included in rations for competition horses. Cocoa beans are used to produce chocolate and are shipped in great quantity to the UK for this purpose. Unfortunately, cocoa beans are a source of theobromine so that containers used to ship it then represent a risk of contaminating the products which are next shipped. There is a real risk of cross contamination. It does not take much chocolate to result in a positive dope test so be careful with the Smarties! We are used to taking Aspirin for pain relief and its active ingredient is salicylic acid, a normal metabolite in horses and a naturally occurring substance in willow (Salix species) and legumes such as alfalfa. Because of this a threshold value is allowed but may not be exceeded.

From the foregoing it can be seen that the greatest risks of diet causing a horse to fail a dope test are essentially two-fold; cross-contamination and poor quality control. Finally, personnel must be briefed about controlling their personal habits. All human food and liquid must be kept well away from the feed room, horses and their feeding utensils. Furthermore, personal illegal drug usage could present a risk since contact between contaminated hands and horse feed could lead to a positive result.

Author: Dr Derek Cuddeford

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