Cardiac troponin I in racing standardbreds.

This research aimed to establish the upper reference limits of cardiac troponin I (cTnI, a heart muscle protein) for healthy standardbred racehorses, and to ascertain whether any increase in this protein was detectable 1-2 hours after a race. The study concluded the reference limits for the cTnI but found no significant differences between cTnI concentrations before and after a race, recommending future research to consider alternate methods for accurate measurements.

Objective and Methodology

• The main objective of this study was to establish the upper reference limits for cTnI in healthy standardbred racehorses. The concentration of cTnI in plasma of these horses was measured both before and 1-2 hours after a race. Blood samples from 586 healthy, racing standardbreds aged 2-14 were used for this purpose. The change in concentration was subsequently determined.
• The study also aimed at identifying any correlations between cTnI concentration and age, and differences in cTnI concentrations by subgroups such as sex, gait, and race classification.
• The methods employed included prospective, observational study, convenience sampling, assay validation, and determination of reference limits in accordance with the ASCVP guidelines. Nonparametric techniques were utilized to calculate 95th and 99th percentile reference limits, after identifying potential outliers.

Results and Conclusions

• The 95th and 99th percentile upper reference limits for all horses, excluding outliers, were found to be < 0.04 ng/mL and 0.06 ng/mL respectively.
• Analysis showed no significant differences in cTnI concentrations based on the factors of age, sex, gait, or race classification. There was also a weak correlation found between cTnI and age.
• Additionally, there were no significant differences found between cTnI concentrations before and after racing in winning horses.
• The researchers concluded that due to the lack of standardization in cTnI assays, the reference limits identified only apply to the Stratus CS immunoassay.
• The study recommends that future studies looking at the effects of high intensity, short duration exercise on cTnI should consider sampling more than 2 hours after racing or using an ultrasensitive assay for accurate measurement of cTnI.