Not all horses are alike in their needs for electrolyte replacement after strenuous exertion. Some deplete their body supplies more quickly or more extensively than others. Endurance horses generally have different needs for electrolyte replacement than do sprinters or cutting horses, and there also are individual differences among horses in any given sport in their need for electrolytes. Some can be helped immensely by judicious use of oral electrolyte supplementation to combat the effects of sweating and stress, while others rarely need it.

The skin pinch test can be used to determine if a horse is dehydrated.

It makes a difference whether or not a horse eats and drinks before or during a competition (as in the case of a long endurance ride), for example whether he is a nervous or calm individual, and so on. A horse’s individual metabolism also plays a role. The endurance horse doing aerobic (with oxygen) exercise has different needs than a racehorse doing anaerobic (without oxygen) exercise, or short, fast work. The properly conditioned event horse works aerobically like an endurance horse rather than anaerobically like a racing Thoroughbred