Urinary excretion of dietary contaminants in horses

Abstract

Reasons for performing study: Presence of drugs is completely prohibited in post racing urine samples by most of racing and competition authorities, even if environmental contamination might occur. Objectives: To assess the daily dose of several contaminants absorbed through the diet that would result in detectable concentrations in urine. Methods: Caffeine, theobromine, theophylline, atropine, scopolamine, bufotenine, DMT or morphine were administered orally to 6 horses, in different dosages, for 3 days before their urine was sampled for regular anti-doping tests. Results: Theobromine, theophylline, bufotenine and morphine daily intake >10 mg, 2 mg, 10 mg and 200 μg, respectively, by a performance horse, were found to result in detectable urinary concentrations. At the 2 tested doses, atropine (5 and 15 mg) and dimethyltryptamine (3 and 10 mg) were not detected in urine. For caffeine and scopolamine, even the lowest dosage tested (5 mg/horse/day and 2 mg/horse/day respectively) induced detectable concentrations of the molecule in urine. Conclusions: Horses fed dietary contaminants, even at level much below the effective dosage, may be positive to anti-doping urine analysis. Further research is needed to gain more confident results on a daily safe intake for caffeine and scopolamine. Potential relevance: Selection of feed materials appears to be of great importance to prevent non voluntary positive result to anti-doping tests. © 2006 EVJ Ltd.