Very few people are aware of the enormous role magnesium plays in a horse’s body. After oxygen, water, and basic food, magnesium may be the most important element needed to maintain health. It is vitally important, yet hardly known.
Magnesium is by far the most important mineral, regulating over 325 enzymes in the body. It increases oxygen delivery to muscle tissue, supports strength and endurance, and helps muscles relax. It also activates enzymes necessary for carbohydrate and amino acid metabolism.
Spring grass is often magnesium-deficient. Horses may become “hot” due to this imbalance. Adding magnesium may calm them. On a cellular level, calcium causes muscle contraction, while magnesium enables relaxation. A lack of magnesium keeps horses in a tense, overreactive state.
Excess calcium can block magnesium absorption. The body may rob bones and tissue for magnesium, which doesn’t show in blood tests until the deficiency is extreme. Symptoms often emerge under stress or competition.
Common Signs of Magnesium Deficiency
- Inability to relax mentally or physically
- Muscle tremors or twitching
- Tight, sore back despite good saddle fit
- Increased excitability after exertion
- Overreactive to brushing, blanketing, or touch
- Bucking, spooking, or resistance to training
- Chiropractic/massage results that don’t last
- Grinding teeth, irregular heartbeat, fatigue
Stress, sweating, travel, and competition all deplete magnesium. Horses may crave salt, worsening the issue. Riders often work these horses harder, creating a cycle of worsening behavior and soreness.
Magnesium Forms & Dosage
– Magnesium Oxide: Common, low bioavailability, may help with ulcers.
– Di-Magnesium Malate: Highly absorbable, minimal laxative effect.
– Magnesium Sulfate: Avoid due to laxative effect.
Feed 6–10 grams daily for horses showing signs. Severe cases may need more. Adjust for stress, work level, or pasture content.
Transdermal Magnesium
Topical magnesium bypasses digestion and is quickly absorbed by muscle tissue. Use before competition for focus, or after for recovery. Forms include sprays, lotions, and salt baths.
How to Monitor Intake
You can’t easily test hay or know exact magnesium levels in many feeds. Learn the symptoms and observe your horse. Magnesium is very safe. Only horses with impaired kidneys should avoid supplementation, and always ensure access to fresh water.
Disclaimer: This article is for informational purposes only and not a substitute for veterinary care. Consult your vet before beginning any supplement regimen.