Horseracing
In horseracing, the International Agreement on Breeding and Racing and Wagering (IABRW), published by the International Federation of Horseracing Authorities (IFHA, 2007), provides guidance for recognised racing and breeding authorities to maintain the integrity of the sport. The agreement addresses prohibited substances and provides guidance on sampling, sanctions, the trainer’s responsibilities, raceday regulations, prohibited substances, thresholds and laboratory services. The objective of the agreement is to protect the integrity of horseracing through controlling the use of substances capable of giving a horse an advantage or being disadvantaged in a race contrary to the horse’s inherent merits. Prohibited substances are defined on the basis of pharmacological action (Table 9.3).
According to the IABRW, The finding of a prohibited substance means a finding of the substance itself or a metabolite of the substance or an isomer of the substance or an isomer of a metabolite. The finding of any scientific indicator of administration or expo sure to a prohibited substance is also equivalent to the finding of the substance. The basis of such rules is to ban the use of any prohibited substance in racehorses at the time of competition; that is a policy of ‘zero tolerance’ except for substances controlled by thresholds. The IABRW states that thresholds can only be adopted for:
1. substances endogenous to the horse
2. substances that arise from plants traditionally grazed or harvested as equine feed
3. substances in equine feed that arise from contamination during cultivation, processing or treatment, storage or transportation.
The list of threshold substances taken from the 2007 publication of the IABRW includes arsenic, boldenone, carbon dioxide, dimethyl sulfoxide (DMSO), estranediol (male horse), hydrocortisone, methoxy tyramine, salicylic acid, testosterone and theobromine. Substances mentioned above which are detected below the thresholds specified in the agreement are not actionable. For any finding of an endogenous substance above the threshold, the horseracing authority may decide itself or at the trainer’s or owner’s request to examine the horse further. In contrast to the policy of ‘zero tolerance’ of drugs currently adopted by racing authorities, certain drugs are permitted at the time of racing in some other jurisdictions. For example, in North America, concentration thresholds and regulations concerning administration have been set for the widely used nonsteroidal anti-inflammatory drugs (NSAIDs) phenylbutazone and its major metabolite ox phenylbutazone, flunixin and ketoprofen (Association of Racing Commissioners International (ARCI) Model Rules of Racing (ARCI 2007a)). According to the ARCI, the finding of more than one NSAID in the serum or plasma will be considered a violation. Furosemide is also widely accepted on the North and South American continents with a threshold concentration in serum or plasma set by the RMTC and regulations regarding administration. The sensitivity of analytical methods used by laboratories to test for drugs in equine body fluids has increased markedly over the past two decades with the introduction of sensitive enzyme-linked immunosorbent assays (ELISAs) and instrumental methods such as gas chromatography–mass spectrometry (GC-MS) and liquid chromatography–tandem mass spectrometry (LC-MS/MS). As a result of this available sensitivity, it is possible that some therapeutic medications may be detected in urine for time periods beyond the point at which the drug continues to exert a pharmacological action. Various approaches have been adopted or proposed to address this issue. In Canada, the racing authorities have adopted a policy of the ‘deliberate non-selection of unnecessarily sensi tive testing methods for specific substances’ (Stevenson 1995). Tobin et al. (1999) proposed the development of threshold values for thera peutic substances based upon the determination of the highest no-effect dose for their primary pharmacological effect, such as the use of the heat lamp–abaxial sesamoid block model for local anaesthetics (Harkins et al. 1994, 1996). Similarly, Smith (2001) questioned the continued adherence to the policy of zero tolerance for drugs registered for equine veterinary use and suggested the use of pharmacologically determined reporting levels. Smith drew an analogy with other fields – veterinary drug residues in feed, food packaging contaminants and food additives – in which the levels of chemicals of no concern for a biological effect have been determined using pharmacological (toxicological) and pharmacokinetic parameters. For example, maximum residue limits (MRLs) and the acceptable daily intake (ADI) have been determined for many drugs used in veterinary practice for the treatment of livestock.
