The urinary excretion of synthetic corticosteroids by the horse.

The research discusses a new method for detecting the use of synthetic corticosteroids in horses by analyzing their urine. This method was tested on various horse breeds and determined that the detection could last for up to six days after a single dose.

Study Methodology

• The researchers developed a radioimmunoassay method, a technique used to measure the concentration of specific antigens by using antibodies.
• This method was used to detect the presence of therapeutic doses of synthetic corticosteroids in horse urine.
• Fourteen proprietary preparations of these steroids were administered to ponies and thoroughbreds, through intramuscular injection.

Key Findings

• The excretion of some preparations of corticosteroids could still be detected six days after a single therapeutic dose was administered intramuscularly.
• The method of administration (intramuscular, intravenous or intra-articular) of a specific corticosteroid (dexamethasone-21-sodium phosphate) did not seem to change how long the steroid or its metabolites were detectable in the urine.
• However, the nature and form of the steroid substantially influenced their urinary excretion, and this was consistent with the duration of its therapeutic action.

Implications and Conclusions

• This research indicates that urine testing can help in tracking the use of synthetic corticosteroids in horses.
• The longevity of the hormone’s presence in urine varies with its physical and chemical structure, thus giving a probable connection to its functional duration.
• Further, the technique provides a way to ensure equine welfare and sporting integrity in horse racing, as misuse of corticosteroids can potentially be monitored.