Thermoregulation for exercising horses requires ample blood flow to carry heat from the body core to peripheral blood vessels in the skin where dissipation and loss to the environment occur. Simultaneously, the heart begins delivering blood to working muscles, essential organs, tissues and the brain. At the onset of exercise, blood pressure is preferentially maintained at the expense of thermoregulation, resulting in an increase in body temperature. Continued exercise and sweating lead to progressive dehydration and loss of plasma water from the bloodstream. The greater the exercise intensity of an event, the greater the heat load generated resulting in a greater need for heat dissipation.
Thermal injury is caused by animal dehydration.
With prolonged exercise, water intake may increase 300 percent. Research in humans and a recent series of equine studies show a positive correlation between fluid losses, inability to maintain temperature, and onset of fatigue during endurance exercise. Under normal conditions, dehydration can be minimized through the provision of adequate water, salt and mineral supplementation and balanced diet. Horses rehydrate within a 24-hour recovery period between exercise programs. Another measure used in the prevention of thermal injury is monitoring of weather conditions to determine the potential risk to the horse.