Supplements for Horses with Equine Metabolic Syndrome Researched

Obesity and insulin resistance (IR) are common problems among horses in many countries and are key risk factors for laminitis. The combination is described as equine metabolic syndrome (EMS), and magnesium and chromium are often contained in supplements given to horses with EMS. This is based on research data in humans with metabolic syndrome showing improved insulin sensitivity.

The first research on the use of chromium in horses was conducted at Kentucky Equine Research (KER) using mature nonobese horses exercised on a treadmill. In that study, supplementation with 5 mg chromium led to improved glucose and insulin dynamics following a meal and during exercise. Since that time, other studies on chromium have shown increased insulin sensitivity, though some researchers have found no difference. The influence of magnesium on insulin and glucose dynamics has not been studied in horses.

A study at the University of Pennsylvania used 13 previously laminitic obese horses that were fed either a supplement with 8.8 g magnesium and 5 mg of chromium or a placebo for 16 weeks. The supplement also contained ginseng, ginger, cinnamon, L-carnitine, and fenugreek. The horses had elevated resting insulin levels, were fed hay low in nonstructural carbohydrates, and were not exercised.

In this study, the supplement had no effect on body weight, body condition, crest size, resting glucose and insulin levels, or insulin sensitivity. The doses of magnesium and chromium supplied were in line with NRC recommendations for magnesium or previous research in the case of chromium. Bioavailable forms were used. An effect might have been observed had the horses been exercised.

Nutritional supplementation is not a quick fix for horses with EMS. Changes in management and exercise are vital.