South African Equine Veterinary Association Congress 2015 Protea Hotel Stellenbosch
adequate Na and Cl for horses that lose substantial sweat during training. For this reason, it is
generally recommended to provide loose salt to horses in hard training – either added to feed or
provided in a separate vessel.
A simple approach for endurance horses in regular training would be to add 1 volumetric ounce of
NaCl powder (1 oz ≈ 30 ml of NaCl powder ≈ 35 g of NaCl because the bulk density of NaCl
powder is ~1.15 g/cm3, as compared to the absolute NaCl density of 2.165 g/cm3) to the
concentrate feed once or twice daily (depending on the amount of training and sweating). During
times of the year when it is hot and more humid, the amount could be doubled to 2 oz in
concentrate meals twice a day. Any excess that is not needed to replace losses would be excreted
in urine and a simple test to assess adequacy of supplementation would be to measure urine Na+
concentration in a morning urine sample collected before the concentrate meal is fed. Adequate
supplementation should result in a urine Na+ concentration >30 mmol/L while a value <20
mmol/L would indicate that more salt could be provided. A value >100 mmol/L would indicate
excessive supplementation and the amount being fed could be decreased in half. At present, there
is no recommendation for supplementation with additional potassium, calcium, or magnesium as
adequate amounts of these minerals should be available through the feed.
What remains unclear is whether or not electrolyte supplementation can improve performance.
If additional electrolytes are going to be administered during competition as oral electrolyte
slurries or by offering salt water as an initial drink, these practices should be started during
training to familiarize the horse with this type of supplementation and to ensure that it does not
cause possible problems. Usually, oral electrolyte slurries are a mixture of NaCl and KCl powders
(at a 3:1 ratio) and about 1 oz is administered wit XX