Electrolytes: clinical applications

Many factors can influence electrolytes in the horse. With the major electrolytes (sodium and potassium), alterations in serum or plasma values do not reflect changes in total body status. However, estimates of electrolyte alterations may be made by combining assessments of body weight changes with plasma sodium values by using the formula of Edelman et al. In planning electrolyte therapy, it has to be remembered that access to green feed or hay is important in correcting any total body potassium depletion and that diets marginal in sodium may interfere with exercise capacity by limiting sweat production. Free access to salt would seem to be the simplest method to ensure adequate sodium availability. Despite the widespread use of various commercial electrolyte supplements administered in horses' feed, most would appear to be unwarranted. Extensive electrolyte deficits are most likely in endurance horses in which substantial electrolyte losses can occur in the sweat. In such cases and when access to grass or hay is limited, supplementation with sodium and potassium chloride may be useful. Bicarbonate administration appears to have no clinical role in endurance or pleasure horses. However, its use as a buffer to limit the extent of lactic acidosis during galloping exercise has not been resolved.