Strategies for voluntary rehydration in horses during endurance exercise.

The research study explores the best methods for rehydration in horses during long-distance endurance exercise. Three different strategies were compared: offering horses water, water after salt paste administration, and a saline solution. The results concluded that drinking saline solution during and after exercise proved to be most effective for rehydration.

Methods of Research

• Thirteen endurance-trained horses aged between 5 and 14 years were used for the study.
• Three strategies for rehydration were compared: drinking water, drinking water after administration of salt paste, and drinking a saline solution.
• The horses had to cover a ride of 62 km in three rounds, with no fluids offered in the first 20km. Fluids were offered at different intervals throughout the remaining distance.
• Bodyweight and fluid intake of the horses were measured during the ride and for up to three hours after the ride.

Results and Findings

• The group of horses drinking a saline solution had a significantly higher total fluid intake than those in the water only or salt paste groups.
• The total plasma protein concentration in the saline group fell below resting values post-exercise, indicating an increase in plasma volume. There were no changes in this group in the other groups.
• Plasma sodium concentration increased in the salt paste group but not in the saline drinking horses, despite their higher sodium chloride intake.
• The horses offered water showed an increased plasma aldosterone concentration post exercise, indicating sodium conservation mechanisms had been activated.
• All treatments led to a decrease in plasma potassium concentration from pre- to post-ride.
• The fastest recovery in bodyweight losses was in the group that drank the saline solution.
• The elevation of plasma sodium concentration in the salt paste group during the ride suggests a disturbance in fluid distribution which could be exacerbated by low water intake, making it the least recommended approach of the three studied.

Conclusions

• The study ultimately concludes that drinking a 0.9% saline solution during and after exercise is the most effective strategy for rehydration in endurance trained horses.
• Using a salt paste immediately before or during exercise could potentially disrupt the fluid balance in the body and thus is not recommended as it could exacerbate dehydration.