Salt (sodium chloride, NaCl) is one of a horse’s fundamental nutrients and cannot be replaced. It affects almost all bodily functions, and both deficiency and excessive intake can cause serious disturbances. In autumn, a horse’s salt requirement changes as sweating decreases and temperatures drop. However, the horse still needs a daily basic intake, because sodium and chloride are essential for, among other things, fluid balance and nerve function.
After summer and the grazing season, when exercise continues but temperatures fall, a horse needs approximately 30–50% less salt than during hot summer weather. Pasture grass naturally contains some electrolytes and water, whereas dry hay is almost salt-free. When transitioning from pasture to indoor feeding, the horse’s natural intake of sodium and chloride decreases. For this reason, the importance of a salt lick or salt supplement increases, even if sweating is reduced.
Essential salt
Sodium and chloride are the most important electrolytes regulating the body’s fluid balance. They help maintain proper blood pressure and the correct fluid levels within cells. Sodium is essential for nerve impulse transmission and muscle contraction. A lack of salt can cause, among other things, weakness, muscle twitching or other muscle symptoms, cramps, fatigue, and reduced performance. Correct salt levels inside cells enable proper muscle and nervous system impulses and contractions and keep water and electrolyte levels in the blood balanced.
Chloride, the other component of salt, is essential for the formation of gastric hydrochloric acid (HCl). Hydrochloric acid helps break down feed and prevents the growth of harmful bacteria in the stomach. Too little chloride intake can impair digestion and may cause gastric issues.
Drinking decreases as the weather gets colder
As temperatures fall, many horses drink less—especially if the water is cold. In this situation, salt is an important driver of thirst, as it encourages the horse to drink more. Adequate thirst, and thus drinking, is one of the most important ways to prevent colic in autumn. It is advisable to add a small amount of salt (e.g. 1–2 tablespoons) daily to the horse’s feed or water if the horse drinks sparingly, because salt activates the thirst response. If a horse does not receive salt, it may drink too little, increasing the risk of colic. This is especially important in autumn and winter.
A lightly worked pasture horse needs approximately 25–40 g of salt per day. This corresponds to about 1–2 tablespoons of coarse salt. A sweating horse in moderate work requires around 50–80 g of salt, and a horse in hard training about 80–120 g.
Sources of salt
A salt lick (natural salt or rock salt) can serve as a basic salt source for horses. It is an easy solution, but not all horses lick enough salt from a block.
In addition to a salt lick, salt can be mixed into feed or water, or provided via separate electrolyte supplements.
Salt deficiency and overdose – symptoms
Salt deficiency may appear in horses as lethargy or loss of appetite. Other symptoms can include muscle stiffness, cramps, reduced sweating, dry skin and mucous membranes, dark yellow and concentrated urine, and in some cases the eating of sand or soil.
Excessive salt intake is rare if the horse always has access to water. If water intake is insufficient, too much salt can lead to dehydration and strain on the kidneys. For this reason, salt should always be provided together with water, for example mixed into a drink or mash.
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