Salt. What is the best form for horses?

Ask The Nutritionist Juliet M. Getty, Ph.D.

Q: Salt. What is the best form for horses and what is the best way to make sure they have salt? Do all horses need salt?


All horses, ponies, donkeys, and minis require salt daily regardless of the season

Pure salt is chemically known as sodium chloride (NaCl). The sodium portion is needed for proper muscle contraction, including the heart muscle, as well as nerve impulses throughout the body and brain. Hay and pasture are very low in sodium.

The chloride portion assists with balancing the blood pH and water flow in and out of the cells (osmotic pressure). It is needed for potassium regulation, allowing for proper muscle contraction as well as water balance. During exercise or hot/humid climates, large amounts can be lost from heavy perspiration. Fortunately, forages (pasture and/or hay) is high in chloride.

Another significant role of chloride is the production of stomach acid, hydrochloric acid (HCl). HCl is needed to start protein digestion. Without enough HCl, horses can become malnourished due to an inadequate pool of available amino acids with which to produce body proteins (such as muscle, enzymes, antibodies, and some hormones).

Salt requirements 

A full-sized horse (1100 lbs or 500 kg) requires a maintenance level of one ounce (two level tablespoons or 30 ml) of salt each day, year ‘round. Heat, humidity, and exercise increase the horse’s need.

Adding salt to your horse’s meals. The best way to meet your horse’s salt needs is to offer granulated salt free-choice. If your horse virtually ignores it, it may be necessary to add salt to your horse’s meals. Before doing this, calculate the amount of sodium from any commercial feeds or supplements. You may need to contact the manufacturer for this amount since it is often is not included on the label. Your goal is to provide approximately 12 grams of sodium per day to a full-sized horse. Each teaspoon (5 ml) contains 2 grams of sodium, so calculate accordingly. However, for palatability, limit the amount to no more than 1 tablespoon (3 teaspoons) per meal.

Salt blocks or unrefined rocks should also be available for additional needs. Keep in mind that these were originally intended for cattle because of their scratchy tongues. Horses, with smooth tongues, cannot possibly lick long enough without irritating their tongues. Consequently, your horse may walk away without getting enough salt.

Types of salt

  • White table salt is heavily processed to remove minerals. It is simply NaCl and is the most economical way to supplement salt. Iodized table salt is also available. Which one to choose depends on how much iodine is added to your horse’s feed or supplements. Two tablespoons of iodized table salt typically contain 2 mg of iodine. Do not exceed 6 mg of iodine per day; too much can damage the thyroid gland especially if there is not enough selenium in the diet.

Salt offered in bulk at many feed stores may contain “prussic acid,” so check the label before purchasing. Prussic acid is often added as an anti-caking agent and is the common name for “hydrogen cyanide.” While cyanide can naturally occur in miniscule concentrations in feedstuffs, I do not recommend deliberately adding cyanide to your horse’s diet.

  • White salt blocks. These are compressed white salt.
  • Mineralized salt blocks. These only offer a few minerals and are bitter-tasting. Since your horse many not lick them adequately, you cannot rely on them to meet your horse’s mineral needs. Many of them have molasses added to overcome the harsh taste and I have seen horses bite off chunks of them like candy. Not what you had intended!
  • Rocks mined from underground salt deposits. A naturally mined salt rock (which is also available coarsely ground) provides a vast variety of trace minerals which plain NaCl cannot offer. Essentially every micro-mineral currently known can be found in these sources. They are naturally chelated (attached) to organic nutrients once found in the oceans such as plants, algae, diatoms, and shells but long since decayed, making them more bioavailable than inorganic mineral sources.
  • Sea salt found on your grocery store shelf. This is produced by evaporating the water from salty oceans or lakes. This is not as good a good choice because the evaporation process leaves behind many trace minerals.
  • This can vary dramatically in its sodium content and may not provide enough to meet sodium needs. Furthermore, the iodine content may be high. When purchasing kelp, make certain it offers the guaranteed analysis on the label. If not, do not risk it.

How to use electrolyte supplements

Electrolytes, if needed, should be given in addition to salt. They are not meant to replace salt. Instead, they are designed to replace perspiration losses and are to be used on an “as-needed basis” following exercise or periods of excessive perspiration.

Salt helps promote that all-important water consumption

However, never add salt or electrolytes to your horse’s only water supply. Plain water must always be available.