Changes in biochemical parameters in horses during 40 km and 80 km endurance races

Changes in Acute Phase Response Biomarkers in Racing Endurance Horses

This study aimed to evaluate if exercise-induced acute phase response (APR) occurs in endurance horses in response to the race. The study included 23 horses competing in an endurance competition with a successfully passed clinical examination before the race. Blood samples were collected before the start and within 30 min after the end of the race. Haematological and biochemical tests were performed and correlated to acute phase biomarkers changes. Values of calprotectin and haptoglobin (Hp) decreased after the races compared to values before, while concentrations of ceruloplasmin and albumin recorded a significant increase. Greater changes in calprotectin values were noted in Arabian horses compared to other breeds. Values of Hp showed a significantly greater decrease after longer races. Based on study results, endurance racing induces APR in horses characterised by significant changes in selected acute phase biomarkers. More pronounced changes were noted at races with higher average speeds, suggesting the need for thorough horse monitoring during exhausting races.

Speed and Blood Parameters Differ between Arabian and Žemaitukai Horses during Endurance Racing

Fédération Equestre Internationale (FEI) has described equine endurance racing as the second largest discipline in the world, above which is only show jumping. The Žemaitukai is an ancient indigenous Lithuanian horse breed known since the 6th or 7th century. The Arabian horse breed is one of the oldest human-developed horse breeds in the world. Compared with other race horse breeds, the muscle tissue of Arabian horses is characterized by significant differences in structure-a predominance of oxidative fiber type I is observed in Arabians, making them the prevailing breed in endurance racing. The Arabian horses are recognized as the leading breed in endurance competitions. Speed, pace, and total time in the race strategy have been extensively studied in human sports, and in contrast, this strategy appears to have been virtually ignored in equestrian sport, despite the potential for contributing to performance optimization. In relation to speed and total time in the race, there are limited data on postrace physical, biochemical, and blood gas parameters of endurance horses. Thus, this study was carried out to investigate the effects of speed on the blood parameters of the Arabian and Žemaitukai horses during an endurance race. Blood samples were taken before and immediately after the exercise. Biochemical and blood gas indicators were analyzed. The study showed significant increases in mean blood gasometrical indicators, such as partial carbon dioxide pressure (8.09-15.18%, p < 0.001); base excess in the extracellular fluid (14.01%, p < 0.001 in the Arabian horses and 172.01% in the Žemaitukai breed, p = 0.006); decreases of the blood electrolyte ionized calcium (4.38-8.72%, p < 0.001) and the hematocrit and hemoglobin values (20.05-20.12%, p < 0.001 in the Arabian horses and 6.22-6.23% in the Žemaitukai breed, p = 0.003-0.004); and decreases in the base excess in the blood values (29.24-39.38%, p < 0.001) and lactate (13.45-31.97%, p < 0.001) in the blood of both breeds in the post-competition horses. Significant increases after competition were determined for the values of creatinine (21.34-30.82%, p = 0.001-0.004), total bilirubin (50.84-56.24%, PH < 0.001), and albumin (2.63-4.48%, p = 0.048-0.001) for both breeds. For the faster Arabian horse breed, recovering after racing took half the time that the local Žemaitukai breed did.