All About Electrolytes

Winter is finally gone, temperatures rising, horses back in work and you may be thinking it’s time to start an electrolyte supplement.  You’re right, but may not realize how to correctly cover electrolyte needs.


The major electrolytes are sodium, potassium and chloride.  They are called electrolytes because they exist in the body in an electrically charged, ionic form.  Electrolytes play a key role in water balance, digestion, formation of urine, thirst, muscle movement, nerve conduction and the beating of the heart.  In short, they are essential for life.

Large amounts of electrolytes are lost in sweat, but those are not the only losses.  There are also electrolytes in urine and manure.  The horse requires electrolytes daily all year.

A horse getting 2% of its body weight in grass or hay every day gets as much as 4 times the basic daily requirement for potassium so this is not something you need to supplement until the horse is in work and sweating. Forage is also a source of chloride, although the levels vary quite a bit.  Sodium is the most problematic because both hay and all other items in the horse’s diet, like grains, brans, etc., are naturally very low in sodium.  The solution to this is plain salt – sodium chloride.

Salt provides the sodium missing from the diet and guards against low levels of chloride in forages.  The average size horse needs 1 ounce of plain salt per day which amounts to 2 tablespoons.  This should be the base of your electrolyte program all year long. Horses not exercising and not obviously sweating will do fine with another ounce of plain salt over the summer months.

However, if the horse is being worked in hot weather or is sweating enough for it to be visible even when not working, you need to replace those sweat losses.  An appropriate product will contain chloride at a level of just a little under twice the sodium.  For every hour of exercise or visible sweating, provide at least 11 grams of sodium.

Getting electrolytes right is a little more complicated than scooping out a supplement that claims to be electrolytes but it’s not that difficult either.  Cover your horse’s plain salt needs first, then read labels and meet those sweat needs.

Example: You found a supplement that is 22% sodium and 38% chloride, the correct ratio. How much should you feed for an hour’s work?

The goal is 11 grams of sodium. An ounce of product = 28.4 grams so at 22% sodium an ounce supplies 6.248 grams of sodium. You need to feed about 2 oz of this product along with your basic need of 1 ounce of plain salt.

Eleanor Kellon, VMD


About Dr. Kellon

Graduate of University of Pennsylvania Veterinary School. Owner of Equine Nutritional Solutions,, industry and private nutritional consultations, online nutritional courses. Staff Veterinary Expert at Uckele Health and Nutrition.
This entry was posted in Equine Nutrition. Bookmark the permalink.

One Response to All About Electrolytes

  1. abigail says:

    Another excellent and informative article. Thank you

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