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

This research article investigates the naturally occurring cortisol levels in the serum and urine of trotting horses to propose threshold values for this hormone, and discusses the complexities in determining such thresholds.

Objective and Method

The primary objective of this paper is to establish thresholds for cortisol levels in the serum and urine of trotting horses. The study involved cortisol analysis of 100 randomly selected post-competition serum and urine samples, using High-Performance Liquid Chromatography (HPLC).

• The purpose of this research is to assist in identifying the use of exogenous cortisol and Adrenocorticotropic hormone (ACTH), which could elevate the naturally occurring levels of cortisol beyond these thresholds.
• Thresholds are important as they help in comparing post-exercise levels of cortisol and detecting any anomalies, which could suggest artificial manipulation for enhanced performance in sport competitions.

Results

Following the analytical process, it was observed that the concentrations of cortisol in both serum and urine bear log-normal distribution. The mean cortisol values were calculated as 61 ng/ml for serum and 49 ng/ml for urine.

• It was found that the probability of exceeding the concentration limits of 230 ng/ml for serum and 394 ng/ml for urine is 1 in 100,000.

Discussion on Threshold Determination

The discussion section of the study explores the challenges inherent in determining thresholds for cortisol levels in horses.

• Cortisol is a hormone naturally released in response to stress and low blood glucose levels. Therefore, physical exertion, such as that experienced in a race, could lead to elevated cortisol levels.
• The challenge lies in distinguishing between what is a natural increase and what might be the result of injecting exogenous cortisol or ACTH to increase endurance or performance.
• This research contributes to the broader understanding of how to establish and apply threshold values for cortisol levels in trotting horses for sportive examinations.