Electrolytes are chemical compounds that form ions when dissolved to produce an electrically conductive medium. Chloride, sodium and potassium are the minerals that are most commonly thought of when the term ‘electrolyte’ is used, but other minerals such as calcium and magnesium are also important in their roles as electrolytes. Electrolytes are important for maintaining osmotic pressure, fluid balance, and nerve and muscle activity.


As a horse begins to exercise it will get hotter and it is vital for the horse to get rid of the extra heat produced to prevent the body from over-heating. Heat is removed from working muscles via the blood to the horse’s skin and to the respiratory tract where it can be passed to the outside environment. Like humans, horses also rely on sweating as their primary mechanism to remove excess heat from the body.

Sweat not only contains just water, but it is also made up of large quantities of electrolytes. During exercise sodium, potassium and chloride are lost in large quantities together with smaller amounts of magnesium and calcium. The combination of water and electrolyte loss will lead to dehydration, which can eventually be fatal. Even slight dehydration can significantly impair performance. A 450-500kg horse has around 300 litres of water in its body and a loss of only 3 litres of sweat would be enough to result in a 10% reduction in performance.

Loss of water and these electrolytes causes, fatigue and muscle weakness and decreases the thirst response to dehydration. Typical symptoms of a severely dehydrated horse will include a dull, depressed expression and glazed eyes, with dry mucous membrane and gums. By the time these symptoms are noticeable, the horse may have lost up to 5% of its body water, which is a very serious situation requiring immediate veterinary intervention. Therefore, it is vitally important that a performance horse starts a competition with optimal levels of fluids and electrolytes in their bodies and that these important nutrients are replaced throughout prolonged exercise.


The amount of sweat that is produced by a horse will depend upon the duration and intensity of the exercise and the environmental temperature and humidity. In the UK typical temperatures are between 50-70 F and, under these conditions, a horse in moderate work will loose between 5-10 litres of sweat per hour. During higher intensity exercise and increased temperature, sweat losses can reach as high as 15 litres per hour.


First and foremost it is essential that horses have continual access to plenty of fresh, clean water. Withholding water even for a short period of time will result in loss of bodyweight and reduction in health and performance. It is good management practice to monitor how much your horse is drinking on a daily basis, as travelling and competing will not only increase your horse’s water requirements, but can also put him off drinking thereby increasing his risk to dehydration.

Salt is the only mineral for which horses have an indisputable appetite for, thereby displaying a degree of nutritional wisdom regarding its consumption. If salt is available, most horses will consume sufficient amounts to meet their needs without overindulging. Natural feedstuffs such as pasture grasses contain little sodium, often less than 0.1%. Most compound feeds do contain some salt but not enough to guarantee sufficient intake for horses that are in regular medium to hard work. Ideally this important electrolyte should be fed ad-libitum in the form of a salt block. Horses at rest will normally consume around 50 grams of salt per day from a salt lick. However, some horses do not reliably use a salt block so you may need to add some salt to your horses feed.

It is vital to adjust the amount of electrolytes fed according to the sweat loss of the horse. If a horse is only in light work then electrolyte supplements do not need to be used every day. However, with a loss of 3 litres of sweat, which can occur in less than an hour in moderate work and conditions, this will be sufficient to reduce performance by 10% and most competition horses will benefit from electrolyte supplementation on a daily basis. As a general rule of thumb, 60 grams (2 ounces) of electrolyte supplementation are required for each hour of exercise in moderate climates.

KER Restore SR

Performance horses, such as endurance horses that are sweating hard and covering large distances may benefit from a specific electrolyte supplement formulated specifically for endurance competition, such asKERx Restore SR. These supplements will contain sodium and chloride but also calcium, potassium and magnesium. If calcium and magnesium losses are not replaced metabolic disturbances such as thumps may occur. These electrolytes should be administered to horses at each vet check and at water stops along the ride. Some electrolytes also contain an antacid to help reduce gastric acid build up caused by irregular feeding intervals during a competition.

It is important to stress that if you are using a concentrated electrolyte paste then the horse must have access to un-supplemented drinking water. Electrolyte pastes are hypertonic (a greater concentration of electrolytes) compared to the blood and will effectively draw fluid out of the horse into the gut if they are not diluted by drinking water. Administering large doses of electrolytes without adequate water intake will result in serious problems including colic, increased dehydration and even possibly death.


When choosing an electrolyte supplement make sure that sodium and chloride are the main ingredients and not glucose. If your electrolyte supplement does not taste of salt it is unlikley that it is going to be effective!

Ensuring adequate fibre intake is important to combat the effects of dehydration. Fibre in the hindgut traps water and electrolytes acting as a reservoir, which can be called upon during exercise. High fibre, soaked feed such as Saracen Re-Covery Mash, is ideal to feed when travelling and competing to aid in fibre intake and hydration status.

Re-Covery Mash is highly palatable, versatile and convenient to use in many different situations. It contains a blend of ’Super-Fibres’, known for their superior digestibility and provision of non-heating calories, plus a source of electrolytes to aid re-hydration. The super fibres help to ‘top up’ the performance horse’s fibre and water intake and, together with electrolytes, helps to maintain optimum hydration and thirst response, during periods of travel, warm weather, sweating, intensive training and exertion. Re-Covery Mash also includes a live yeast to support gut flora and stabilise the pH of the gut, as well as vitamin E to support normal muscle function and recovery. Saracen Re-Covery Mash should be soaked before use and will take 5 – 10 minutes to soak in warm water, or 15 – 20 minutes in cold water. The amount of water added will depend upon the individual horse and the reason for feeding the mash.