Alterations of fluid and electrolyte balance in thoroughbred racehorses following strenuous exercise during training.

The study investigates the changes in the fluid and electrolyte balance in Thoroughbred racehorses after intense exercise during routine training.

Study Overview

The research was an observational study aimed at understanding the impact of strenuous exercise on the fluid and electrolyte balance in 16 Thoroughbred racehorses. This was achieved by observing changes in a set of variables – including serum concentrations of sodium, potassium, chloride, and protein; blood pH levels; plasma and urine osmolality; body weight; and the fractional excretion of sodium, potassium, and chloride.

Key Findings

• During exercise, the research team observed a number of changes, including increased sodium concentration in the blood; increased sodium fractional excretion; decreased chloride concentration in the blood; and decreased chloride fractional excretion.
• They also found increased osmolality of plasma and urine; the horses lost weight; had decreased blood pH (indicating acidemia); and increased lactic acid concentration.
• In other words, exercise led to more sodium in the blood, higher amounts excreted via urine, less chloride in the blood, lesser excretion of it, more concentrated urine and plasma, body weight decline, acid buildup in the blood, and an increase in the production of lactic acid.

Significance and Implications

• The observed changes in plasma chloride and acidity levels in the Thoroughbred racehorses diverged from previously reported findings in endurance horses, which indicated decreased chloride levels and metabolic alkalosis, a condition where the body’s pH increases beyond normal levels. In contrast, the racehorses in this study demonstrated a fall in blood pH (acidemia) and a drop in blood chloride levels.
• The study attributes the acidemia in the racehorses to the production of lactic acid through anaerobic glycolysis. This process happens when the muscles start producing energy without enough oxygen, which is common in high-intensity exercises, leading to the generation of lactic acid.
• These findings are important for understanding the physiological responses of racehorses to strenuous exercise; they can inform more effective training practices, better horse care, and possible intervention measures for treating exercise-related issues.