Your horse sweats more during the summer, making electrolyte supplementation worth considering. But electrolytes alone will not protect against dehydration. Your horse needs to have enough sodium (salt). One ounce per day (two tablespoons) is adequate for maintenance during cool months, but hot, humid weather calls for at least two ounces per day, and more if your horse is in work of any kind.

Article by By Juliet M. Getty, Ph.D.