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Zilpaterol Feed Contamination Update

Following intensive discussions with European counterparts over the last week, the Irish Horseracing Regulatory Board in conjunction with the British Horseracing Authority can today issue the following update relating to the zilpaterol feed contamination. 




  1. What is zilpaterol and how is it regulated in horseracing?


  • Zilpaterol is a beta-2 agonist with anabolic properties, used in the USA and some other countries as an animal-feed additive to promote weight gain, principally in cattle. Zilpaterol is not approved for use in the EU.
  • As a beta-2 agonist, zilpaterol falls within Article 6E of the International Agreement on Breeding, Racing and Wagering (IABRW), meaning it cannot be administered to a racehorse at any time during its career.
    • Under Article 6E, there is an exception for beta-2 agonists which may be administered to a horse if prescribed by a veterinary surgeon as a bronchodilator at an appropriate dose. As zilpaterol is not approved for use in horses, this exception does not apply.
  • Consistent with Article 6E, all racing jurisdictions within the European Horserace Scientific Liaison Committee (EHSLC), including France, Ireland and Great Britain, prohibit the use of zilpaterol at all times, both on raceday and out-of-competition.
  • To be clear, zilpaterol is a beta-2 agonist with anabolic properties – it is not an anabolic steroid.



  1. Previous issues


  • Zilpaterol has been detected in Thoroughbred horse samples previously, by analytical laboratories in USA (2013), Hong Kong (2013), Mauritius (2019). In all cases, contaminated horse feed was the source of these findings.


  1. Current issues


  • Zilpaterol has been reported in several post-race samples from France, which were analysed by the French analytical laboratory LCH, from race meetings held on 30 August 2020 onwards.
  • To date, there have been no post-race samples which have reported positive for zilpaterol in any other European jurisdiction.
  • A common feed, GAIN, was reported to have been fed to all horses returning affected post-race samples. Following testing, GAIN issued a statement confirming that zilpaterol was present in three feeds (Racehorse Cubes, Racehorse Mix and Opti-Care Balancer).
  • In a second statement, GAIN confirmed that the source of zilpaterol contamination was molasses, supplied by the company ED&F Man Ltd.


  1. Testing for Prohibited Substances


  • Raceday and out-of-competition testing falls into two categories:
    • Anti-doping, and
    • Medication control.
  • Medication control refers to the control of substances which are prohibited on raceday – these are mainly veterinary medications, which are permitted for use in training, but prohibited on raceda
    • Laboratories used by the EHSLC group have harmonised Screening Limits for such substances.
  • Anti-doping refers to the control of doping agents, such as anabolic steroids, which are prohibited at all times – these substances cannot be administered to a racehorse at any time during its career.
    • Laboratories used by the EHSLC group (European jurisdictions) aim to detect such substances at a Recommended Target Sensitivity. The Recommended Target Sensitivity is the minimum concentration that the EHSLC laboratories are expected to achieve. This harmonised approach is supported by the International Federation of Horseracing Authorities (IFHA).
  • Anti-doping research and development is constantly evolving, in order to maintain pace with those who seek performance enhancement.
    • As such, all laboratories are encouraged to seek improvements beyond the Recommended Target Sensitivity, where possible, for substances which are prohibited at all times. This is because these substances simply have no place in horseracing.
  • LCH (the analytical laboratory for France Galop and Le Trot) and LGC (the analytical laboratory for the BHA and IHRB) are both able to detect zilpaterol in urine, blood and hair to the Recommended Target Sensitivity. LCH have, however, been operating to a more sensitive level for zilpaterol.
  • This has potential implications for a horse which races in more than one jurisdiction (e.g.) two post-race urine samples with the same concentration of zilpaterol may currently be reported as positive in one country, and negative in another.


  1. Current action


  • In order to address the current issue in an internationally harmonised manner, the IFHA have convened an Expert Panel comprising regulatory veterinarians, analytical chemists and administrators. The Expert Panel report has now been considered by the EHSLC Board.
  • There is agreement to the following recommendations:
    • All racing jurisdictions should offer Elective Testing for zilpaterol, where contaminated feed is suspected to have been fed
    • Elective Testing should be performed in the country in which a horse holds an entry (e.g.) if an Irish horse holds an entry in France, the Elective Test should be performed at LCH.
    • Both the IFHA and the EHSLC endorse an approach where no regulatory action is taken against any screening findings for zilpaterol in an Elective Test, where it can be demonstrated that the horse was likely to have been fed contaminated feed.
    • Harmonisation: racing jurisdictions and their analytical laboratories will work through the IFHA to determine whether reporting limits for zilpaterol, and other key substances which are prohibited at all times, can be harmonised

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