These two minerals have very specific body functions. Lack of either sodium or chloride can cause problems for your horse. They are important in maintenance of the acid-base balance of the body, passage of waste materials out of the cells and water metabolism. Sodium also functions in the contraction of muscles, including the heart muscles. Lack of salt causes loss of appetite, rough hair coat, reduced growth, and lower mild production.
Horses also become fatigues easily.
Lack of salt may be the reason your horse becomes tired and does not perform as well as usual when it is hot and humid. As temperature, humidity, and intensity of performance increases, horses sweat more, losing more salt. Salt is also lost in urine and feces. So, the daily salt need is more. The normal salt requirement is about two ounces daily.