The muscular activity associated with training and competition results in a rapid increase in body temperature. The only way for horses to lose this excess body heat is via sweat production; in fact efficient muscle function is dependent on it.
Sweat also represents the major route of fluid and electrolyte loss in horses, taking with it significant amounts of water and electrolytes from the body.
Electrolyte composition of sweat
Chloride – 7gms/litre
Sodium – 4gms/litre
Potassium – 1.3gms/litre
Magnesium – .13gms/litre
Calcium – .25gms/litre
Phosphorus – .03gms/litre
Obviously these electrolytes must be replaced as quickly and efficiently as possible, either in the diet or by oral administration. We talk about the Dietary Electrolyte Balance (DEB) as being the total amount of electrolytes but a standard type mixed diet is usually not enough to meet the required DEB. To demonstrate this point, consider a basic diet of 6kg Grass/Hay + 3kg Oats + 3kg Sweet feed with no added electrolyte supplement. If we analyse this diet it equates to:
Crude Protein 1200gm 1300gm
Digestible Energy 30mCals 30mCals
Potassium 145gms 55gms
Sodium 18gms 42gms
Calcium 60gms 47gms
Magnesium 19gms 22gms
Chloride 46gms 80gms
This diet has a low DEB with Chloride, Magnesium and Sodium levels being low. Potassium is rarely deficient in diets based on grass and hay. An increase in the work of a horse will create a requirement for an increase in electrolyte supplementation. Horses do not store sodium, potassium or chloride from one day to the next. Therefore electrolytes need to be adjusted according to the work level of the horse and the environmental conditions. Working in hot conditions will create a higher rate of sweat and therefore a need for greater replacement. When not in work the horse needs less, if over supplemented, it will increase water intake and urine loss.
A correctly formulated Electrolyte supplement should contain Chloride and Sodium at a ratio of approximately 2:1 as well as Calcium and Magnesium at low levels.
The equine kidney has developed to handle forage diets which are high in Potassium and low in Sodium. As long as the kidneys are functioning properly and the DEB is correct, they will regulate and maintain the body’s Electrolyte levels.
The idea of acid and alkaline Electrolyte supplements is now regarded by equine physiologists as unnecessary. Horses can develop a mild metabolic acidosis after intense exercise and may develop a metabolic alkalosis in situations of heavy sweat loss. In both these cases so long as there is sufficient Chloride in the DEB then the horses kidneys will sort out its own acid/base balance. Vetpro Equine Electrolytes are a neutral PH composition.
It is difficult to assess a horses Electrolyte status from a blood test, samples of blood and urine need to be taken at the same time. Consult your veterinarian for this.