Electrolytes for Horses: When and How to Use Them

Electrolytes for horses replace the salts lost in sweat: mainly sodium, chloride and potassium, with smaller amounts of calcium and magnesium. This guide covers why horses need them, how they differ from plain salt, when to feed them, and how to use them safely alongside fresh water.

What electrolytes do

Electrolytes are minerals that carry an electrical charge when they dissolve in body fluids. They help the body keep a normal fluid balance and are involved in normal nerve and muscle function. Sodium and chloride are the main electrolytes in the fluid outside the body's cells, and potassium is the main one inside them.

Why horses lose so many

Horses cool themselves mainly by sweating, and they can sweat heavily: several litres an hour during hard work in hot or humid weather. Horse sweat is also unusually salty. It is more concentrated in electrolytes than the horse's own blood, so a sweating horse loses salts faster than it loses water.

That matters for drinking. Thirst is driven largely by the concentration of salt in the blood, and because sweat removes salt as well as water, a horse that has sweated heavily may not feel as thirsty as you would expect. Replacing electrolytes helps restore the normal drive to drink.

Salt or electrolytes?

Most horses need some salt every day, whether or not they are working, because grass and hay are naturally low in sodium. A 500 kg horse at rest needs roughly 25 g of salt a day, and more in hot weather or hard work. A salt lick can help, but how much each horse takes from a lick varies a lot, so many owners add a measured amount of salt to the feed instead.

Plain salt replaces sodium and chloride. An electrolyte supplement adds potassium, magnesium and calcium as well. Forage is usually rich in potassium, so a horse at rest on good hay or grass is rarely short of it. After heavy or repeated sweating, though, a balanced electrolyte replaces more of what has been lost.

When to feed electrolytes

• After work that makes your horse sweat, especially in warm or humid weather.
• Around travel, competitions and long days out, when horses often drink less than usual.
• During spells of hot weather, even for horses in light work.
• As part of the daily ration for horses in regular hard work.

Horses cannot store spare electrolytes for later, so it is better to feed them regularly around work and hot weather than in one large dose.

How to feed electrolytes safely

• Always provide fresh, clean water. Electrolytes only help if your horse drinks, and they should never be the only water available.
• In water, offer a choice. If you add electrolytes to water, put a bucket of plain water alongside so your horse can choose.
• In feed, dampen it. Mixing the powder into a damp feed helps it stick and get eaten.
• Use the rate for bodyweight. Follow the feeding guide rather than guessing, and do not go above it without advice.
• Try it at home first. Introduce electrolytes before a competition or long journey, so the taste is already familiar.

When your horse needs more than electrolytes

Call your vet if your horse is dull or lethargic, stops eating or drinking, passes very little or very dark urine, has gums that feel dry and tacky, or has skin that stays tented when you pinch it. These can be signs of dehydration that needs veterinary attention, not just a supplement.

HerdLab Hydration Support

HerdLab Hydration Support is our horse electrolyte supplement. It provides sodium chloride and potassium chloride with magnesium sulphate, calcium lactate and dextrose in an apple-flavoured powder that can be mixed into feed or water. It is fed by bodyweight, from 15–20 g a day for ponies up to 300 kg to 30–60 g a day for horses over 600 kg. To make an isotonic solution after heavy sweating, the guide is 10 g per 5 litres of water for one to three days, with plain fresh water also available. The product page has the full feeding guide, or you can explore the full HerdLab range.

Frequently Asked Questions

Can I give my horse electrolytes every day?

For a horse that sweats regularly, yes, as long as fresh water is always available. Feed at the rate on the label for your horse's bodyweight.

Is a salt lick enough?

For a horse at rest it can help, but intake from licks varies a lot between horses. Many owners add measured salt to the feed so they know how much their horse gets, and use an electrolyte supplement after sweating.

Should electrolytes go in feed or in water?

Either works. Feed is the simplest way to know your horse has had the full amount. Water can encourage drinking, but always offer plain water as well.