The Importance Of Electrolytes

by Karen McGivena July 25, 2023 5 min read

The Importance Of Electrolytes

Written by Briony Witherow MSc, BSc, RNutr.

Electrolytes are body salts essential for fluid balance, muscle, and nerve activity. The main electrolytes to note are sodium, potassium, and chloride.

When looking at electrolyte use, it is important to consider the role of electrolytes in the diet more widely and the different reasons for supplementing.

It is hard to discuss electrolyte use without first mentioning salt. Even horses fed their full complement of concentrate feed or vitamin and mineral supplement are likely to require additional salt (sodium chloride). This is because forage alone is inherently low in sodium and, most compound feeds and supplements do not meet requirements. The justification for the latter is twofold: firstly, an element of flexibility is necessary due to daily requirements being dependent upon electrolytes lost during exercise (as sweat) and secondly that salt has the potential to degrade other nutrients when included in a compound feed. 

For those at rest or light work on a high forage diet, the provision of 0.02g per kilogram bodyweight of sodium (10g for a 500kg horse) should meet minimum requirements. 

The best way to achieve this is by adding salt to the diet, either in the bucket or by providing a salt lick.

Table salt (sodium chloride) is around 40% sodium. Feeding 30g (a heaped tablespoon) of table salt per day will provide 12g of sodium which is sufficient to meet the maintenance requirements of a 500kg horse. Alternatively, or in addition to this, a salt lick can be provided. This may be more suitable for those in rest to light work as salt intake from blocks/licks alone can be inconsistent. However, a rough idea of intake can be gained by monitoring how long the block lasts – as a guide, a 1kg salt block should last a 500kg horse around 30 days, a 2.5kg block 75 days.

For horses in moderate work and upwards (or those working in hot/humid environments), we would need to consider the addition of an electrolyte product. The main purpose of electrolytes is to stimulate thirst response (through re-establishing electrolyte balance), and, in doing so, maintain or restore hydration.  For horses at rest and light work, the provision of salt (sodium chloride) alone is typically sufficient, as those on a high forage diet will typically receive sufficient potassium from their forage ration. It is when horses are working harder (sweating more and at higher risk of becoming dehydrated) that specific electrolyte supplementation is essential.

Why is hydration important?

  • A loss of just 2% of water in the horse’s body can have negative effects on performance.
  • Water is lost through various mechanisms, one of which is through sweat. Sweat is made up of water, a protein called latherin (which helps to spread the sweat) and electrolyte minerals. On a typical UK summer day, a 500kg horse can lose 5-7 litres of sweat per hour of steady trotting and cantering. This can rise to 10-12 litres per hour under conditions of high heat and humidity. Along with water, it is estimated that ~10g of electrolytes are lost per litre of sweat.
  • Electrolyte balance is vital to trigger thirst response, making not only water but electrolyte provision key considerations for any hydration strategy.
  • Fibre in the gut acts as a reservoir for water and electrolytes, making ample fibre provision an essential consideration. For those that may not eat much forage when travelling, this can be a key piece of the puzzle to address to promote hydration, performance, and recovery.
  • Dehydration is strongly associated with higher risk of colic, gastric ulcers and urinary tract issues, making it not only a concern for performance but overall health.

Provision of Electrolytes: Best Practice

Electrolytes can be offered daily for those in moderate to hard work (or exercising in hot/humid environments) or those in less daily work when competing/training hard on occasion. On the day of an event, electrolytes can be provided before, during and after exercise (requirement dependant on the discipline and work intensity).

Ultimately, success of electrolyte provision hinges on appropriate monitoring of water intake. Knowledge of average water intake for each horse and how these changes during training and competition is key to tailoring electrolyte provision to an individual.

Powder or Syringe?

Use of a powdered electrolyte product or syringe to some extent is down to personal preference (both horse and rider). However, typically powdered supplements are designed for daily/regular use, where syringe products can be more convenient at events, travelling or, to top up existing electrolyte provision.

When feeding any electrolyte (syringe or powder), it is key to ensure adequate water intake. This is important as the increased presence of electrolytes in the system post feeding will trigger the thirst response. As such, ensuring water is available where electrolytes have been provided (particularly in a concentrated source such as a syringe) and monitoring the response is considered best practice.

As with any supplement or management, the better you know the horse, the more we can tailor the approach. For horses that are known to be poorer drinkers or that you are still getting to know, monitor water intake and consider using electrolyte products conservatively at first (in parts for example a third or half a syringe at a time) and monitor response. The tricky thing to navigate is that we know the more dehydrated a horse gets, the more diminished the thirst response, so it is striking a balance between stimulating this and monitoring water intake. For fussy drinkers, having a buffet of plain, electrolyte water and flavoured water options can help (or even popping a handful of a tasty mash or their usual feed in the bottom of a water bucket to help flavour can also work well).

How to feed electrolytes

  • Prepare the recommended daily amount based on the horse’s size and workload.
  • If the duration of exercise or travel is long, provision of electrolytes can be divided accordingly.
  • Electrolytes can be fed in a wet feed or (ideally) diluted in water. Regardless of feeding method, electrolytes should always be offered alongside plain water.

Timing of electrolyte administration has been indicated to optimise effectiveness. Please see recommendations below:

Type of Work/Exercise

Timing of Electrolyte Provision


Short duration

Provide ONE hour before exercise.

To aid in ensuring adequate hydration. Note that even where horses are worked for short periods, sweating may continue post exercise adding to fluid and electrolyte losses.


Provide within ONE hour before travel. If travelling >2hrs incorporate electrolyte provision along with water at rest stops.

Travelling even in cooler weather will typically result in loss of water and electrolytes through sweating.

Long Duration

Provide ONE hour before exercise and at each opportunity during the event as appropriate alongside water. For example, for endurance horses at vet gates or between phases for event horses.

Where possible, only offer sips of water straight after exercise until the horse has returned to his resting respiratory rate at which point electrolytes and free access to water can be provided.

This aims to ensure you start the event with a well-hydrated horse and further provision of electrolytes and access to water will help to keep hydration levels topped up during exercise.


During training is a good opportunity to get your horse accustomed to receiving electrolytes rather than presenting them only at a competition. Just like introducing any other supplement to the diet, electrolytes should be introduced gradually to increase chances of successful feeding.

Everyday Electrolytes vs Restore Lyte?

There are many electrolytes on the market suited for daily use such as ‘Everyday Electrolytes’, the difference between these and ‘Restore-Lyte’ powder or liquid is that the latter combines electrolyte and muscle glycogen (energy store) replenishment. As such, Restore-Lytecan be used in place of Everyday Electrolytes where an additional boost to the recovery process is required. For example, for those with heavy training and competition schedules, or re-fuelling on the go (such as vet gates, between classes or phases), a combination electrolyte and energy product such as Restore-Lyte may be recommended.

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