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Hydration and Electrolyte Depletion a Continual Challenge
by: Stacey Oke, DVM, MSc
May 20 2010, Article # 16376
Hydration and electrolyte depletion remain important factors to consider in endurance horses. Yet the impact of electrolyte supplementation on performance remains unclear and potential side effects may exist, relayed Harold Schott II, MS, DVM, PhD, Dipl. ACVIM, a professor at Michigan State University's College of Veterinary Medicine at the 2010 Kentucky Equine Research Nutrition Conference held in Lexington April 26-27.
In Schott's presentation, "Challenges of Endurance Exercise: Hydration and Electrolyte Depletion," Schott explained that exercising horses, particularly endurance competitors, can lose both body water and electrolyte stores that could lead to serious medical problems or even "exhausted horse syndrome" if not properly addressed.
In adverse ambient conditions, an exercising horse can lose up to 10-12 liters of sweat per hour. Not only does this result in total body water loss, but also the electrolytes sodium, chloride, and potassium.
Over the past few decades, electrolyte supplementation has become a mainstay in minimizing fluid and electrolyte losses. Research has demonstrated that horses exercising for more than an hour or two in hot, humid climes will likely benefit from supplementation with salt water.
"An easy recipe for hardworking horses in the summer would be 1-2 oz (1 ounce is about 25 g) of an equal mix of table salt and lite salt added to the grain twice daily," advised Schott. "Next, an initial drink of salt water during the first few minutes after exercise (or at rest stops during the exercise bout) is another strategy that may be useful on especially hot and humid days."
Schott did add that electrolytes are not innocuous and that potential adverse effects could develop secondary to supplementation.
For example, there is some evidence that horses can be over-supplemented, resulting in an inadvertent increase in blood levels of sodium and chloride. Further, one study found that horses fed concentrated salt slurries had an exacerbation in the number and severity of gastric ulcers.
Schott did note, "In theory, excess electrolyte administration should not be a problem as long as competing horses are provided frequent access to water and continue to drink."
For more information on the conference, speakers, presentations, and to view video interviews, visit www.ker.com/news/2010/04/kentucky-equine-research-17th.html.
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