[Cortisol levels in blood and urine of trotting horses].

Statistical analysis of normally occurring cortisol levels in serum and urine of horses served to recommend thresholds for this corticosteroid in these body fluids, as application of exogenous cortisol as well as ACTH may elevate the cortisol concentrations above the proposed threshold. The present study contributes to the general issue of how to establish thresholds for trotting horses upon sportive examination. 100 randomly selected post competition serum and urine samples, respectively, were submitted to cortisol analysis by means of HPLC. Concentrations of the endogenous corticosteroid in serum and urine followed a log-normal distribution with mean values of 61 and 49 ng/ml, respectively. The probability was 1: 100,000 to exceed concentration limits of 230 (serum) and 394 ng/ml (urine). Designation of thresholds for cortisol has proven problematic and is discussed here.