Tiludronic acid can be detected in blood and urine samples from Thoroughbred racehorses over 3 years after last administration.

This research reveals that traces of tiludronic acid, a banned substance in racing horses younger than three and a half years, can still be detected in the horses’ blood and urine samples three years after its last administration.

Objectives and Methods of the Research

• The primary purpose of the study was to determine if traces of tiludronic acid, a kind of bisphosphonate, could be found in horses’ blood and urine samples more than 40 days after its last known administration.
• To conduct the study, the researchers used a retrospective cohort, by selecting horses who were previously treated with Tildren, which contains tiludronic acid, from clinical records.
• Out of the chosen 24 horses, 21 were still in active race training. The research team then collected their blood and urine samples for analysis.
• The researchers used ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) to detect the presence of tiludronic acid in those samples.

Findings of the Study

• The research detected traces of tiludronic acid in all the tested horses, even in two that were given the drug three years prior to the sampling.
• The estimated concentration of the substance in the blood, collected at least two years post-administration, was extremely low, less than 0.3 ng/mL, throughout the tested group.
• Its concentration in the urine samples was generally lower than in the blood samples, but there were inconsistencies. Some horses showed significantly higher levels: up to about 16 ng/mL almost 1 year post-administration in one horse and about 3.7 ng/mL at almost 3 years post-administration in another horse.

Conclusions and Limitations

• The research concluded that evidence of tiludronic acid administration in a horse could still be obtained over three years after its last known administration. This could have significant implications on regulations and testing protocols in horse racing.
• However, the study had some limitations. For one, most of the tested horses were older than the primary target group: young Thoroughbred racehorses below three and a half years old. The use of this restricted age group thus may not fully represent the wider horse population.
• Additionally, the researchers only had a single sample from most horses, limiting their ability to draw definitive conclusions about elimination profiles of the drug in the animals’ bodies.