Variation of pre- and post-race cardiac troponin concentrations in Thoroughbred and Arabian racehorses

In horses, cardiac troponins are specific and sensitive biomarkers of myocardial injury. Increased cardiac troponin T (cTnT) and cardiac troponin I (cTnI) concentrations may indicate myocardial damage, but the physiological release is also possible post-exercise or race. In this study conducted to investigate the effects of racing on cTnT and cTnI concentrations in Thoroughbred and Arabian racehorses, blood samples were collected from seven Thoroughbred stallion and eight Arabian stallion racehorses, aged between 3 and 6, before and 30 min after a 1400-metre race. The mean cTnT concentration increased from 0.007 ± 0.001 ng/ml to 0.008 ± 0.001 ng/ml in Thoroughbred racehorses and from 0.007 ± 0.002 ng/ml to 0.008 ± 0.001 ng/ml in Arabian racehorses. The mean cTnI concentration increased from 008 ± 0.001 ng/ml to 0.142 ± 0.005 ng/ml in Thoroughbred racehorses and from 0.008 ± 0.002 ng/ml to 0.165 ± 0.054 ng/ml in Arabian racehorses. The increases in post-race cTnT ( P < 0.05) and cTnI ( P < 0.001) concentrations of both breeds were statistically significant. The results of the study suggested that racing in racehorses has an effect on the myocardium and this effect was reflected as an increase in cardiac troponin. However, it would be useful to make multiple measurements at certain time intervals after the race to accurately determine whether the increase is physiological or pathological.