Electrolytes should be given to athletes that are exercised and worked routinely. If your horse is trained for a discipline that requires extreme speed or stress that causes profuse sweating, your horse needs electrolytes. Your are typically exceeding the amount of sodium, potassium, chloride and other ions that are necessary in regular body function. The profuse sweating is a good indicator that you need to supplement these ions in the form of a well balanced electrolyte additive to their feed.