Oral Presentation 24th International Conference of Racing Analysts and Veterinarians 2026

The salicylic acid problem – a metabolomic solution? (130358)

Lance Brooker 1 , Paul Berghouse 1 , Lauren Kennan 1 , Joshua Klingberg 1 , Kaiyu Li 1 , Christopher Tangvisethpat 1 , John Keledjian 1 , Carly Garling 2
  1. Australian Racing Forensic Laboratory, Racing NSW, Sydney, New South Wales, Australia
  2. Racing NSW, Sydney, New South Wales, Australia

The use of anti-inflammatory salicylates such as acetylsalicylic acid (aspirin) and methylsalicylate, is controlled by the application of thresholds for the primary metabolite, salicylic acid (2-hydroxybenzoic acid, SA). This is necessary as SA is a natural constituent of plants and is therefore expected to be consumed and excreted to some extent by horses. Previous research has investigated the plasma pharmacokinetics and urinary metabolism and excretion of both exogenous salicylate therapeutics and feed containing naturally elevated levels of SA (e.g. lucerne hay) and was used to set and subsequently assess the international thresholds (6.5 µg/mL plasma, 750 µg/mL urine respectively).1-5 These research groups acknowledge that the thresholds may not be appropriate in situations where lucerne hay is consumed, but do not propose a workable solution other than withholding feed on race day.

Lucerne hay (alfalfa hay) is grown extensively in south-eastern Australia and is widely available as feed for racehorses. The ARFL’s recent experience is that infrequently, but regularly, groups of horses are flagged for elevated plasma SA on screening, with a lesser number subsequently verified during quantitative confirmation. While in these cases doping as a cause is possible, it was considered highly unlikely, as the horses involved came from the same collection locations but originated from different trainers and riders (e.g. equestrian events with individual competitors).

The ARFL and Racing NSW sought to develop an approach that could appropriately classify these samples as not originating from doping with exogenous salicylates. This paper will describe an administration trial conducted with exogenous salicylates and lucerne hay containing elevated SA, and the analysis results of the collected plasma samples using quantitative LCMSMS and semi-quantitative LCHRMS. We will then describe the process and outcome of an investigation into a possible metabolomic solution to the problem of elevated SA levels detected in equine plasma.

  1. Moss, M.S. et al. Normal and post-administration concentrations of salicylic acid in thoroughbred horses. Proceedings 6th International Conference of Racing Analysts and Veterinarians, Hong Kong. 1985. 97–102.
  2. Beaumier, P.M. et al, Presence of salicylic acid in Standardbred horse urine and plasma after various feed and drug administrations. Equine Vet. J., 1987, 19, 207-213. https://doi.org/10.1111/j.2042-3306.1987.tb01381.x
  3. Lakhani, K.H. et al. Estimation of the critical threshold value for presence of salicylic acid in the urine of thoroughbred horses. Proceedings 15th International Conference of Racing Analysts and Veterinarians, Newmarket. 2004. 67–77.
  4. Schenk, I. et al. Evaluation of salicylic acid concentrations in horse blood and urine with regard to the actual threshold, Proceedings 19th International Conference of Racing Analysts and Veterinarians, Philadelphia: ICRAV; 2012, 115-124.
  5. Buntenkötter, K. et al, Pharmacokinetics and in vitro efficacy of salicylic acid after oral administration of acetylsalicylic acid in horses. BMC Vet. Res., 2016, 13, 28. https://doi.org/10.1186/s12917-017-0955-1.