An increase in body temperature, either as a result of exercise, travelling or high environmental temperature will cause the horse to sweat. The evaporation of this sweat helps the horse to cool down and regulate his body temperature.
Sweating causes fluid loss, together with the loss of body salts or electrolytes, which are contained in the sweat.
The important electrolytes are Sodium and Chloride, Potassium, Calcium and Magnesium and they play many key roles in the body, but especially muscle contraction, the nervous system, and maintaining the fluid balance around cells.
Potassium is usually supplied in abundance in the horse’s diet, as most forages such as pasture, hay and haylage are high in potassium.
Sodium and Chloride are found at much lower levels in forages, and even for horses in light work, sodium and chloride need to be provided on a daily basis.