Electrolytes for Horses: Why Timing Matters More Than You Think

Electrolytes are one of the most talked about (and often misunderstood) aspects of equine nutrition. Many riders only think about them after exercise, yet their role begins long before a horse even sets foot in the arena.

For horses in work, particularly those training hard and competing regularly, understanding when to feed electrolytes and how they function is key to supporting hydration, recovery and consistency.

What Are Electrolytes?

Electrolytes are minerals that carry an electrical charge when dissolved in fluid. In horses, the most important include:

• sodium
• chloride
• potassium
• calcium
• magnesium

These minerals are essential for maintaining fluid balance, supporting muscle contraction and enabling normal nerve function. When a horse sweats these electrolytes are lost, often in significant quantities.

Unlike humans, horses lose relatively high concentrations of electrolytes in their sweat, which makes replenishment an important consideration for horses in work.

How Much Do Horses Lose During Exercise?

Horses rely on sweating as their primary cooling mechanism, and the volume of fluid lost can be substantial.

Research suggests:

• horses can sweat 5–7 litres per hour during moderate work
• during more intense exercise, this can increase to 10–15 litres per hour
• endurance horses may lose 20–25 litres of sweat over prolonged periods of exercise

Each litre of sweat contains meaningful amounts of sodium, chloride and potassium. Over the course of a training session or competition, these losses can quickly accumulate, particularly in warm weather or during sustained effort. Replacing these losses with a balanced electrolyte supplement for horses such as UltraElectroS can help support hydration during periods of increased demand.

Signs of Salt Deficiency

 

Your horse may be lacking salt if they display any of the following signs:

• Wood chewing
• Excessive salt lick intake
• Eating/licking soil
• Lack of energy
• Muscle tremors
• Apathy
• Allergies
• Staggering

Some of these signs can be indicators of other deficiencies and/or more serious, neurological issues so always consult your vet if you have any concerns.

 

How Much Salt Does a Horse Need?

Salt - made up of sodium and chloride - accounts for the majority of electrolyte loss.

At maintenance, a 500 kg horse typically requires around 50 grams of salt per day. However, once a horse begins regular work, this requirement increases significantly. During periods of sweating, daily needs can rise dramatically depending on workload, temperature and duration of exercise.

In practical terms, many horses in work are unlikely to meet these increased requirements through forage and salt licks alone, particularly when training intensity builds.

When Should You Feed Electrolytes?

A common misconception is that electrolytes are only necessary after exercise. In reality, this approach often means you are reacting to losses that have already occurred.

Research indicates that when electrolytes are fed in advance of exercise, they can be absorbed and available within the body during work. This allows them to support hydration as sweating begins, rather than trying to restore balance afterwards. This shift in thinking is important. Rather than “chasing losses”, feeding electrolytes ahead of exercise helps prepare the horse for the demands placed upon them and allow them to replace them as needed. That said, post-exercise feeding still plays a role. Replacing what has been lost remains important but it is only part of the picture. Many riders now include electrolytes for competition horses as part of their routine to support hydration before, during and after work.

Why Water Alone Isn’t Enough

After exercise, it is common to focus on water intake. While access to clean, fresh water is essential, water alone does not replace the electrolytes lost through sweat.

Electrolytes help regulate how fluid is distributed and retained within the body. Without them, water may pass through the system without being effectively utilised. In some cases, replacing water without electrolytes may even reduce the horse’s natural drive to drink. Studies have shown that providing horses first with a small amount of warm, salty water can encourage them to then drink more water than they would normally.

This is why balanced electrolyte replacement is considered an important part of supporting hydration following work.

Can I Feed Too Much Salt?

The body will excrete excess salt via the urine so it is unlikely that you can feed too much salt or cause any harm, unless you are feeding excessively high levels over a long period of time and not providing sufficient clean water to encourage the horse to drink. As it is not very palatable in large amounts, horses will also normally reject excessive amounts of salt in feed or water.

Do Electrolytes Cause Ulcers?

There is a long-standing perception that electrolyte supplementation may contribute to gastric ulcers. Often likened to “rubbing salt in the wound”. This perception largely stems from a study done in endurance horses where horses given electrolytes developed gastric ulcers but as with any aspect of feeding and research, context matters.

These horses were given almost 500g of electrolytes in water not feed (feed helps act as a natural buffer), over an 8 hour period. That is very different to feeding normal levels of electrolytes in feed, twice a day - the daily serve of Equell UltraElectroS for example, is 60g for a horse in moderate work

Extremely high doses, poor formulation or inappropriate feeding practices may not suit every horse, but balanced electrolyte supplementation, used correctly alongside fibre feed, is widely considered safe for horses. If your horse is currently undergoing treatment for ulcers it is unlikely that they need electrolytes and any supplementation should be discussed with your vet to check for unwanted interactions with medication. 

The Gut Connection

Electrolyte balance is closely linked to digestive health. The hindgut plays an important role in fluid absorption, and a stable microbial environment supports efficient digestion and nutrient utilisation.

When the gut is compromised - whether through stress, dietary change or travel - this can influence how effectively the horse manages both hydration and recovery. For competition horses in particular, where routines are frequently disrupted, maintaining digestive stability becomes even more important.

This is where a gut-first approach to nutrition comes into its own, supporting the systems that underpin performance from within. Sodium chloride in feed and hindgut supplements such as Gut Food contributes to the normal function of digestive enzymes, supporting overall digestion and gut health.

Supporting Recovery from the Inside Out

Recovery is not simply about replacing what has been lost, but about how efficiently the body restores balance.

Nutrients that support normal energy metabolism, alongside those that help maintain a stable gut environment, can contribute to how well a horse copes with training and competition demands. B vitamins, for example, play a role in normal energy metabolism, while prebiotic fibres support the microbial population within the hindgut.

B vitamins play a central role in how efficiently the horse produces and utilises energy during and after exercise. They are essential for converting nutrients into usable fuel via aerobic metabolism, helping to reduce reliance on less efficient pathways associated with fatigue. Supporting adequate B vitamin status may also help limit the build-up of lactic acid during exercise, which is linked to muscle fatigue and slower recovery. In addition, research has shown that B-complex supplementation can improve exercise endurance and reduce markers of fatigue, supporting more efficient recovery following work. Nutritional strategies that support cellular energy metabolism, fluid balance and metabolic resilience through prebiotic hindgut support therefore play an important role in helping horses recover, reset and maintain consistency between efforts. Particularly important for event horses or competition horses with back to back events mid season.

The Take-Home Message

Electrolytes are fundamental to supporting hydration, normal muscle function and optimal recovery in horses, particularly those in moderate to hard work.

Horses can lose significant volumes of fluid and electrolytes during exercise, and their requirements increase accordingly. Feeding electrolytes only after exercise may miss an important opportunity to support the horse before losses begin and supplementing ions in real time.

A more effective approach considers timing, balance and the wider role of the digestive system. Products such as UltraElectroS electrolyte supplement for horses are designed to help replace salts lost through sweat and aid hydration during exercise whilst also providing hindgut and recovery support through inclusion of B vitamins and prebiotic fibres.

Because when hydration, gut health and recovery are supported together, the result is a horse that is better prepared for the demands of training and competition.

And in performance horses, preparation is the key to success!