Related Experiment Video
Updated: Jul 15, 2026

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids
Published on: April 25, 2016
Urinary excretion of dietary contaminants in horses
F Respondek1, A Lallemand, V Julliand
1ENESAD, Nutrition et Santé Digestive des Herbivores, 26 boulevard Petitjean, BP 87999, 21079 Dijon cedex; and LCH, 15 rue de Paradis, 91370 Verrieres le Buisson, France.
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 microg, 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 antidoping 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.
Related Concept Videos
Comparative Excretory Systems
Drug Excretion: Miscellaneous Routes
Hepatic Drug Excretion: Enterohepatic Cycling
Post-release drugs and metabolites can be reabsorbed into the body from the intestine. For conjugated metabolites like glucuronides, reabsorption requires enzymatic hydrolysis by intestinal microflora. This...
Enhanced Elimination of Poison
Antidotes serve a crucial role in counteracting the effects of poison by inhibiting enzymes responsible for producing harmful drug metabolites. In some cases, these toxic metabolites can be neutralized by endogenous cosubstrates, which are maintained at specific concentrations to prevent interaction with cellular macromolecules and subsequent cell death.
Renal excretion is the...
Drug Elimination: Non-Renal Routes
Drug Elimination by Renal Route: Tubular Reabsorption

