Supplement Use in Performance Horses

Take a look at some commonly fed supplements and the theories behind their use.

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Why do horse owners use feed supplements? Ask 10 different owners, and you’ll probably get 10 different answers. But if you ask David Marlin, PhD, founder of Science Supplements, suggests that typically, he’ll say owners are generally looking to solve a particular problem when they elect to feed a supplement.

Agar et al. (2016, Veterinary Record) have also learned that the majority of riders perceive a difference in their horses after feeding supplements. But, is this a real change or a placebo effect? There is still much to be studied regarding the efficacy of many supplements.

At the University of Maryland’s Department of Agriculture and Natural Resources’ 2016 Mid-Atlantic Nutrition Conference, held March 23-24, in Hunt Valley, Maryland, Marlin described commonly fed supplements and deconstructed the theories behind their use:

  • Calcium: Marlin said supplementing calcium for calming effects horses has become a trend in the U.K. and Europe. While many horse owners feel it works, there is no evidence to prove it does, he said. Plasma calcium concentration is strictly regulated by the horse’s body, which he said begs the question: Does supplementing calcium really have a significant impact?
  • Cobalt: Cobalt is a trace element that is required in very small doses, but is essential to vitamin B-12 makeup. Marlin said cobalt could potentially contribute to an increase in erythropoietin (which stimulates red blood cell production), possibly resulting in a performance-enhancing effect. Excessive cobalt can also act as a carcinogen and cause cardiovascular problems, reproductive disorders, and blood problems. The use of cobalt in equine sport is under intense scrutiny and supplementation above basic requirements has been banned by many racing jurisdictions.
  • Electrolytes: Electrolyte balance is important in the equine athlete. Too many electrolytes in the system can deter a horse from eating it. Additionally, oversupplementation will cause the horse to drink more and the kidneys to work overtime to maintain proper physiologic balance. On the other hand, too few electrolytes can cause poor performance, fluid imbalances, episodes of tying up and/or thumps (synchronous diaphragmatic flutter), and chronic electrolyte depletion. Marlin said undersupplementation and chronic deficiency appears much more common than over-supplementation. He cautioned that many horses do not adequately regulate salt intake from salt blocks/licks. As such, Marlin recommended that equine athletes be offered electrolytes in daily feed based on workload and weather conditions, aiming for a slight excess.
  • Turmeric/Curcumin: Turmuric can contain 3-4% curcumin—which is thought to have anti-inflammatory and anti-cancer properties—and its popularity has recently exploded in Europe. Despite a sharp rise in scientific publications about turmeric, few examine efficacy in horses. While both turmeric and curcumin are considered natural herbal supplements, this does not automatically qualify them as safe, Marlin said. Adverse effects have occurred in humans, including contact dermatitis, loose bowels, and decreased appetite.

Take-Home Message

There’s copious information—and misinformation—about supplements circulating on the Internet, and Marlin said the use of social media has led to an explosion of inaccurate and misleading information regarding supplements. Supplements are sometimes legitimately needed and quite appropriate to fill a gap in the diet, while other times they aren’t needed at all. As such, owners should turn to equine nutritionists, Extension specialists, and veterinarians with their questions regarding horses’ diets and potential problems with creating a dietary imbalance.


Written by:

Nettie Liburt, MS, PhD, PAS, is an equine nutritionist based on Long Island, New York. She is a graduate of Rutgers University, where she studied equine exercise physiology and nutrition. Liburt is a member of the Equine Science Society.

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