Challenges in detecting substances for equine anti-doping.

The artificial increase of the physical capability of horses using drugs is well known in racing and other equine sports. Both illicit and therapeutic substances are regarded as prohibited substances in competition in most countries. Some countries make distinctions for a few, specific drugs which are, however, allowed for use in other countries. The primary objective in the case of doping control is the detection of any trace of drug exposure, either parent drug or any of its metabolites, using the most powerful analytical methods which are generally based on chromatographic/mass spectrometric techniques. Of major concern in horseracing is the absence of a single organization regulating the anti-doping framework; instead of this, individual racing authorities provide rules and regulations often resulting in variations in the applied doping control programmes of different countries. The aim of this paper is to review the recent literature (approximately from 2012 to mid-2016) to highlight the numerous and diverse challenges faced in doping control of racing and equestrian sports, including the detection of designer drugs (anabolic steroids or stimulants) and of other emerging prohibited substances, such as peptides and noble gases in horse urine and plasma. Moreover, the application of 'omics' techniques (especially of metabolomics) deserves attention for establishing possible fingerprints of drug abuse as well as the evolution of instrumental analysis resulting a powerful ally in the fight against doping in equine sports.