Control of the misuse of testosterone in castrated horses based on an international threshold in plasma.

This research article focuses on developing an effective way to control and detect the misuse of testosterone in gelded (castrated) horses, using an established threshold in their plasma. It uses a method called liquid chromatography-mass spectrometry (LC/MS) to quantify low levels of testosterone, and proposes based on the results a rounded up threshold of 100 pg/mL of free testosterone in plasma. This proposed plasma threshold is found effective in controlling testosterone misuse in geldings.

Method of Detection

• The research developed a liquid chromatography-mass spectrometry (LC/MS) method for quantifying low levels of free testosterone in gelding plasma. Liquid chromatography-mass spectrometry is an analytical chemistry technique that combines the separative power of liquid chromatography with the detection ability of mass spectrometry. This is a valuable method for detecting traces of chemical substances in complex mixtures.

Establishing Thresholds

• The study conducted a population study of 152 post-race plasma samples to determine the mean concentration of plasma testosterone. Through relevant mathematical transformations, tentative thresholds of 49 or 55 pg/mL were suggested.
• However, for ease of application, a rounded-up threshold of 100 pg/mL of free testosterone in plasma was proposed. This would correspond to a risk factor of less than 1 in 10,000, ensuring a highly accurate threshold for detection.

Testing the Proposed Threshold

• To validate their proposed threshold, the study administered Testosterone Suspension 100 to six geldings and measured the duration for which testosterone could be detected in their plasma or urine.
• It was found that the detection times in plasma and urine matched, with an average of 14 days. The maximum detection time was 18 days in plasma and 20 days in urine, suggesting the viability of the proposed threshold for efficient monitoring.

International Adoption

• This study gained relevance as its results were later reproduced in Europe, validating the proposed threshold of 100 pg/mL of free testosterone in plasma.
• The proposed threshold was subsequently adopted by the International Federation of Horseracing Authorities (IFHA) in October 2013. The implementation of this threshold system aids in maintaining fair competition by controlling the misuse of testosterone in gelded horses.