Metabolic responses in endurance horses during racing in relation to uric acid profile, leucocytes, heart rate and plasma biochemical parameters

Uric acid has stronger pro-oxidant than antioxidant properties during equine endurance events and thus, limits performance and has serious repercussions on health. The aim of the study was to investigate the changes in uric acid, leucocytes, plasma biochemical parameters and heart rate in metabolic endurance horses. Thirty Arabian endurance horses were physically examined and blood samples were collected pre and post-race. After physical examination, the successfully completed (n = 10) and metabolic disordered (n = 20) endurance horses were identified. Blood samples in heparinised vacutainer tubes were used for the determination of uric acid, triglyceride, creatine kinase, aspartate transaminase, packed cell volume, lactate, total protein and plasma protein. Blood sample in ethyl diaminotetra-acetic acid vacutainer tubes were used for the analysis of leucocytes. The age, body weight, heart rate, humidity and ambient temperature were also recorded. One way Analysis of variance and pairwise correlations were used for the analysis. A value of P ≤ 0.05 was considered as significantly different. The mean values of uric acid, lactate, leucocytes, plasma protein, total protein, heart rate, creatine pinase and Packed cell volume were significantly different between the successfully completed and metabolic disordered endurance horses P < 0.0001), respectively. The mean values of aspartate transaminase and triglyceride were significantly different between the successfully completed and metabolic disordered endurance horses: P < 0.0130 and P < 0.0004, respectively. There were significant positive correlations between uric acid and lactate (r = 0.5196; P < 0.0271), between uric acid and plasma protein (r = 0.6025; P < 0.0175), between uric and Packed cell volume (r = 0.5206; P < 0.0268), between uric acid and triglyceride (r = 0.5541; P < 0.0170) and between uric acid and heart rate (r = 0.5629; P < 0.0150) in the metabolic disordered endurance horses. In conclusion, heart rate, triglyceride, blood lactate and packed cell volume were significantly associated with uric acid, a biomarker of oxidative stress. Therefore, uric acid could be used to evaluate performance and health status in endurance horses during training and endurance events.