Muscle damage, hydration, electrolyte balance and vasopressin concentrations in successful and exhausted endurance horses.

The research investigates the differences in hydration, electrolyte balance, muscle damage, and Arginine vasopressin (AVP) concentrations in successful and exhausted endurance horses. It indicates that exhausted horses show an increased release of AVP, potentially making it a useful biomarker for early exhaustion and hypovolaemia.

Objective of the Study

• The study aimed to understand the disparities in hydration levels, electrolyte balance, muscle enzyme concentrations, and AVP levels among successful and exhausted endurance horses. The goal was to understand if there was a correlation between these variables and the performance of the horses during an endurance event.

Methodology

• The researchers divided eighteen endurance horses, into two groups based on their performance in a 76.2 km endurance competition — a successful group having thirteen horses and a smaller exhausted group with five horses.
• Jugular venous blood samples were collected at different intervals: before the event (BF), and at vet-gates, at 30km (PH1), 53.6km (PH2), and at the end (PH3). Various parameters including Na, Mg, CK, LDH, MHT, TSP, ALB, CREAT, and LA were measured and analysed from these samples.

Findings

• Successful horses showed significant increases from BF in Na at PH1, in Mg, CK, LDH at PH2, and MHT, TSP, ALB, CREAT, and LA at PH3, along with a decrease in Cl at PH2 and Ca at PH3.
• Exhausted horses had higher MHT, Na, Ca, TSP, CREAT, LA, and AVP than successful horses at PH2 and PH3. On the other hand, Cl was observed to be lower in exhausted horses. Additionally, the velocity during the ride was higher in the exhausted group.

Conclusion

• The study concluded that there are lab findings supporting this theory: exhausted endurance horses displayed a deeper state of dehydration and increased levels of AVP. This suggests that AVP could be an effective biomarker for early exhaustion and hypovolaemia. Importantly, the results indicated that AVP levels remained unaffected by the speed of exercise or the distance covered in successful horses.