Magnesium Deficiency in Horses: Early Warning Signs and Fixes
Magnesium drives more than 300 enzyme reactions in the equine body, quietly regulating everything from nerve transmission to energy production. Yet forage analyses show that many modern hays hover below the 0.20 % Mg benchmark, while hard work, travel, and lush spring pasture drain reserves even faster. The result is a horse that looks fit on paper but reacts to every rustle of the wind.
Why Deficiency Happens in Well-Fed Horses
Magnesium is absorbed in the small intestine, but high-potassium grass, rapid gut transit after intense exercise, and chronic stress can all block that pathway. Commercial concentrates supply only two to five grams per daily ration—barely meeting National Research Council minimums for a 500 kg (1,100 lb.) horse at rest, let alone one in training.
Subtle Signs to Watch For
Before blood magnesium ever dips, behavior and muscle tone usually change. Owners often notice a tighter back, fasciculations along the ribcage, reluctance to stand for the farrier, or a horse that spooks at routine sounds. Over time, hoof quality may suffer and insulin regulation can wobble, raising laminitis risk in easy keepers.
Confirming the Shortfall
Standard serum tests rarely catch marginal deficiency because the body draws on bone stores to keep blood values stable. A more reliable clue is a diet audit: if hay or grass provides less than 7.5 g Mg per day for a 500 kg horse, and concentrate adds little, the odds of a shortfall are high. Veterinary thermography and hair analysis can add supporting evidence, but practical feeding adjustments remain the real solution.
Correcting the Gap
First, rebalance the ration. Aim for 0.3–0.4 % magnesium in the total dry-matter intake, which equates to about 10–15 g elemental Mg daily for most adult horses in work. Choose a form that the gut can actually absorb—cheap oxides vary wildly, while Epsom salts quickly become laxatives. Nupafeed® MAH® Magnesium bonds pharmaceutical-grade Mg to aspartate-hydrochloride carriers, moving it across the gut wall without digestive upset. Riders typically notice a calmer eye and looser stride within a week of the loading dose, then maintain with half the amount.
Management Tweaks That Help the Supplement Stick
Keep a predictable routine, offer free-choice salt to balance electrolytes, and cool horses promptly after hard work to slow gut motility. If turnout is on lush spring grass, provide low-potassium hay before grazing so the horse isn’t famished when he hits the pasture buffet.
Give Your Horse a Magnesium Advantage
Don’t let a silent mineral gap steal focus and performance. Shop Nupafeed MAH® Magnesium Supplements and see the difference in calmness, muscle suppleness, and overall well-being.
