Principles that will help you know when and how to supplement horses with electrolytes.

One topic that horse owners repeatedly wonder about is that of electrolytes and specifically how and when they should be used. In general, horses participating in most equestrian sports don’t need electrolyte supplementation. A horse that sweats during a short training ride or competition might lose some body water and salts, but these losses are usually replenished quickly upon eating hay, drinking, or visiting the salt block. However, there are other situations, involving horses that compete in distance riding pursuits (endurance, competitive trail, or the cross-country phases of eventing or combined driving), for example, when electrolyte supplementation is important to the horse’s safekeeping and welfare. Electrolytes are salts–notably potassium, chloride, sodium, calcium, and magnesium–and are essential to proper body function.

Research conducted at endurance and competitive trail rides has demonstrated that many horses experience the greatest loss of fluids and electrolytes within the first 20 miles of exercise. Long-distance transport to an event adds to dehydration and electrolyte losses before the horse even begins to perform, so this, too, must be factored in. A horse that participates in protracted exercise, such as a distance trail horse, is working for many hours and, at times, for multiple consecutive days. Staying ahead of salt and fluid losses is instrumental in maintaining hydration, efficient muscle function, and the ability of the horse to perform to a safe standard and with enthusiasm for his work.

So, let’s look at some principles that will help you decide when it is appropriate to provide electrolyte supplementation.

Energy into Locomotion

For muscles to obtain energy for locomotion, food substrates must be converted into energy fuel. In the horse, approximately 70-80% of this metabolic conversion to energy is liberated as heat. In the best situation, heat is dissipated from the inner recesses of the horse’s body as sweat, which cools by evaporation of “water” from the skin. Even with moderate exertion during hot weather, a horse sweats. Think about what happens when you exert yourself even slightly on a hot day: Whether you are walking out to the pasture to retrieve your horse, are grooming your horse, or are riding at trot or canter, you sweat. This is a normal physiologic response of man or horse to muscular movement, particularly when the ambient conditions are hot and/or humid, or when the exertion is significant. The inherent problem in some equestrian pursuits is the persistence and duration of your horse’s sweating process