The electrolyte debate heats up
Often clients will consult their veterinarians regarding conditioning, nutrition, supplementation and managing horses exercising in extreme heat. These recommendations have traditionally included electrolyte supplementation. Joe Pagan, PhD, of Kentucky Equine Research calls electrolytes "essential nutrients for the performance horse," and adds that along with being essential for maximal performance, electrolyte supplementation "helps horses rebound from hard work sooner, return to feed quicker and begin the necessary rebuilding phase that occurs after exertion."
The essential elements of the electrolyte debate used to be which electrolyte mix to recommend, how much to use and when to administer it. Recent developments from the world of endurance racing, however, have added another perhaps more important question to this electrolyte discussion and might well affect how equine veterinarians advise their clients in the future.Are electrolytes even necessary during a race?
The exceptional success of the French and Belgium endurance teams in recent international events has brought electrolyte use into question, since both of these teams administer minimal to no electrolytes during a competition. "Electrolyting is only the tip of the iceberg," says Leonard Liesens of the Belgium team. Riders from these countries are stressing harder pre-ride conditioning and more complete feeding before competition as means of avoiding electrolyte supplementation during races.
Research shows that during the average 160-km (100-mile) ride in moderately hot weather, a horse will lose about 30 to 40 liters of fluid, which includes 300 to 400 g of sodium chloride, 45 to 50 g of potassium and a small amount of magnesium. European veterinarians question whether this volume of loss can or should be replaced with the use of oral supplementation. They reason that highly concentrated electrolyte salt pastes given by mouth contribute to both oral and gastric ulceration and that this irritation can slow down the digestive process, which is a greater detriment to an exercising horse than any potential electrolyte imbalance.
"Additionally, one of the more serious repercussions with overuse of electrolytes is that athletes will third-space fluids," says Heidi Smith, DVM, an equine practitioner working at an international level at endurance events. "In other words, they begin to pull fluid back into the gut to bring the concentration of electrolytes there back to normal when they cannot transport the electrolytes across the gut wall fast enough or when the concentration is already high in the bloodstream and cells because of dehydration."
The end result may be that supplementation with concentrated electrolyte paste actually worsens dehydration in exercising horses and contributes to metabolic problems rather than helping to avoid them.
The other side of the debate
Research from the Ontario Veterinary College at the University of Guelph has shown that endurance horses and event horses with less pronounced fluid and electrolyte alterations during a competition were more successful than those with greater losses. This conclusion makes intuitive sense, and European veterinarians and riders would surely agree with these findings. But the debate still rages on as to the best method of reducing fluid and electrolyte losses. And the best answer may turn out to be the simplest.