Gastric emptying of oral rehydration solutions at rest and after exercise in horses.

This study investigates how quickly horses expel various types of rehydration solutions (ORS) from their stomachs both at rest and after completing exercise. They found that most of the fluid is emptied within 15 minutes, irrespective of exercise, and that stomach electrolyte levels shifted over time although these shifts were not affected by the types of rehydration solutions used.

Research Methodology

• The researchers tested four types of oral hydration solutions – isotonic, cold isotonic at 5 degrees Celsius, another with glucose and a hypertonic fluid – on four Standardbred horses at rest in one part of the study.
• In another part, isotonic fluid was given to the horses after they completed treadmill exercise at 70 per cent of their maximum oxygen consumption (VO2 max) until they were exhausted or at rest.
• In both parts, each horse was given a single 8-liter dose of the respective fluids through a nasogastric tube.

Procedure and Measurements

• The researchers observed the gastric emptying (GE) and the electrolyte concentrations (sodium – Na+, potassium – K+ and chloride – Cl-) in the stomach content, taking measurements at 15-minute intervals over a period of one hour.

Key Findings

• The data presented showed that 90 per cent of the fluid was emptied from the horses’ stomachs within the first 15 minutes of ingestion in both parts of the study, whether the horses were at rest or had just performed exercise.
• There was no significant difference observed in the electrolyte concentrations in the stomach content based on the type of rehydration fluid ingested.
• However, changes in electrolyte concentration were noticed over the time period, reflecting the body’s physiological adaptation to the hydration process.

Conclusion

• Based on their findings, the researchers indicated that the speed of GE is not likely to significantly impact the rehydration process in horses, given that most of the fluid is expelled quickly (within 15 minutes).