Electrolytes are minerals found in the horse’s body that carry an electrical charge. Electrolytes are important for a range of functions, including nerve signalling, muscle contraction and fluid balance.

Key electrolyte minerals include sodium, chloride, potassium, magnesium, and calcium. [1][2][3][4] Ensuring your horse has balanced electrolyte levels can support optimal performance, recovery after exercise, and promote hydration.

Your horse needs to obtain electrolytes from their diet to replenish the electrolytes lost in sweat, urine, and other bodily functions.

Horses at maintenance or in cool climates typically get adequate levels of electrolytes from their forage, except sodium. For these horses, adding plain salt is typically sufficient to balance electrolyte requirements.

Horses in heavy exercise or horses in hot climates can sweat profusely and lose large amounts of electrolytes. If these electrolytes are not replaced through supplementation, these horses can experience exercise intolerance, muscle weakness, and dehydration.

This article will review the function of electrolytes in the horse’s body, the effects on dehydration and performance and how to best supplement electrolytes in the equine diet.

Why Electrolytes Are Important for your Horse

Electrolytes are minerals that carry an electric charge when dissolved in a liquid. Electrolytes are found in blood, within cells and in the fluid surrounding cells (interstitial fluid).

These minerals are vital for most bodily functions, including nerve transmission, the movement of muscles, and regulating blood pH and fluid balance.

Horses lose electrolytes through drooling, respiration, urinating, defecating, and sweating. These minerals must be replaced by dietary sources to maintain overall health and prevent dehydration.

In severe cases, deficiencies or imbalances in electrolytes can lead to death. This is a risk for horses competing in endurance events, foals with diarrhea, and for emaciated horses.

Electrolyte loss via sweating during prolonged exercise may not be adequately replaced through feeds. [5] In these cases, supplementing your horse with an electrolyte formulated for equine athletes is recommended.

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Key Electrolyte Minerals for Horses

The most important electrolytes in mammals, including horses, are:

  • Sodium (Na+): The most abundant electrolyte in the blood serum, sodium maintains hydration and fluid volume within the body. In horses, sodium is necessary for regulating thirst. [1]
  • Chloride (Cl-): The second most prevalent electrolyte in the blood serum, chloride regulates fluid and pH balance in the body. [1]
  • Potassium (K+): Plays a key role in maintaining cell function and is required for muscle contraction and relaxation. [2]
  • Magnesium (Mg2+): Necessary for muscle relaxation and nerve function. [3]
  • Calcium (Ca2+): Essential for muscle contraction and nerve function. [4]

Electrolyte Loss in Horses

The most significant loss of electrolytes occurs during sweating. However, illness can also lead to electrolyte loss that needs to be addressed through supplementation or infusion.

Sweating

Sweating is the primary mechanism by which horses regulate their body temperature. A significant amount of water and electrolytes are removed from their body via sweating during exercise and in hot weather.

Horses can produce up to 15 L of sweat per hour during moderate exercise. Sweat volume and composition will vary according to the intensity of exercise, ambient temperature, humidity, diet, and adaptive response to the environment. [8]

Based on one study, an hour of sweating at a rate of 15L per hour produces the following electrolyte losses: [7]

  • 105 grams of chloride
  • 60 grams of sodium
  • 30 grams of potassium
  • 4.5 grams of calcium
  • 1.5 grams of magnesium

When sweating is excessive, heat exhaustion and dehydration can result in fatigue and poor performance. In severe cases, dehydration can be fatal.

Illness

Illness