Effect of diet on thoroughbred horses with recurrent exertional rhabdomyolysis performing a standardised exercise test.

This research explores the impact of diet on Thoroughbred horses susceptible to recurrent exertional rhabdomyolysis (RER). It specifically compares the effects of three dietary plans on the horses’ metabolic and clinical parameters during standardized exercise. The study suggests that while diet might not significantly influence rhabdomyolysis or the metabolic response to exercise, it could potentially lower pre-exercise heart rates in RER-affected horses, indicating a calming effect.

Objective and Methodology

• The goal of the research was to analyze how different diets impact clinical and metabolic parameters in horses diagnosed with recurrent exertional rhabdomyolysis (RER) during a standardised exercise test (SET).
• The study involved eight Thoroughbred horses: five with RER and three healthy ones.
• Three dietary plans were considered: one high in soluble carbohydrates (CHO), the second high in fat, and the third was an excess carbohydrate diet providing 135% of the Digestible Energy (DE) of the other two diets.
• The diets were provided in a crossover design for three-week intervals, post which the horses underwent a near-maximal SET.

Procedure and Measurements

• The tests and measurements included changes in heart rate (HR), plasma lactate, plasma glucose, total plasma solids, packed cell volume (PCV), muscle lactate and muscle glycogen concentration.
• The readings were taken immediately before, during and five minutes post-exercise.
• Also, Serum creatine kinase (CK) activity, which is an indicator of muscle damage such as rhabdomyolysis, was measured prior to, and four hours post-SET.

Findings and Interpretation

• The study found that horses on the high-CHO diet had higher mean pre-SET PCV and pre-SET HR compared to horses fed the fat diet.
• Most notably, horses with RER on the high-CHO diet had the highest pre-SET heart rates compared to those on low-CHO and fat diets.
• No significant differences in CK activity, a marker of rhabdomyolysis, were found in response to the dietary treatments.
• However, it was inferred that the diet might have a calming effect on Thoroughbred horses with RER as it could lower pre-exercise heart rates and decrease pre-exercise PCV, especially when fed a fat-rich diet.

Limitations and Further Considerations

• Although the study didn’t confirm a diet effect on rhabdomyolysis or the metabolic response to exercise, it hinted at potential diet-induced changes in a horse’s cardiovascular response to exercise.
• Suggests a need for further detailed studies on how diet affects horse physiology and further potential connections between diet and performance in RER horses.