Horse Health

How and why to use electrolytes

Stephanie Mapletoft, MSc Equine Science, leads the nutrition team at Pure Feed and helps customers on a daily basis with nutritional advice for their horses.

Sodium, potassium, chloride, magnesium and calcium are the five main electrolytes that your horse requires. They play vital roles within the body and are involved in most bodily functions including digestion, fluid regulation, the acid-base balance (pH) of the body and neurological functions such as muscle contractions.

Electrolytes are lost from the body daily in urine, faeces and sweat. Horses use sweating as the primary way to remove excess heat from the body. Horses can produce 10-15 litres of sweat per hour during intense exercise so can lose a lot of electrolytes through sweating; approximately 9g of electrolytes per litre of sweat. Sodium, chloride and potassium are present in large quantities in sweat, and smaller amounts of magnesium and calcium.

Whilst grass, hay and hard feed do provide some electrolytes, in most cases it is not enough to meet your horse’s requirements if they are in more than light work. It is common for horses not to be receiving enough electrolytes from their diet. This applies in particular to sodium as forage in the UK is often low in sodium.

For horses in light work that are consuming fresh grass and a balancer, adding some table salt will provide the additional sodium and chloride that they need. For a typical horse adding 25g per day of table salt to their feed will provide them with enough sodium to meet their requirements. Whilst giving your horse access to a salt lick will provide them with additional salt, several studies have concluded that horses do not regulate their intake to match their requirements with a salt lick.

"Electrolyte deficiency is linked to fatigue and muscle weakness"

Electrolyte deficiency Electrolyte deficiency can take months to become a problem, but signs include poor performance, decreased sweating, muscle problems such as tying up, poor recovery after exercise, thumps and increased risk of fractures. Electrolyte deficiency is linked

to fatigue and muscle weakness which will both affect performance. It can also cause a decrease in the horse’s thirst response, leading to dehydration. Sodium is the main electrolyte responsible for your horse’s regulation of thirst.

Feeding an electrolyte supplement Providing an electrolyte supplement in the diet is particularly important for the performance horse to prevent an electrolyte deficiency.

"it is important to make sure that your horse is well hydrated and has sufficient electrolytes"

Performance horses that are in a higher level of work or worked for longer periods of time, are likely to be producing more sweat and thus losing more electrolytes and water from their body. To enable them to perform at their best, it is important to make sure that your horse is well hydrated and has sufficient electrolytes in their body before competition.

Feeding an electrolyte daily, as opposed to just adding an electrolyte supplement after intense work or before a competition is advisable. This will allow the horse to excrete any extra electrolyte that it doesn’t need and help prevent an electrolyte deficiency. Feeding only after competitions could cause your horse to refuse their feed if they are not used to being fed electrolytes. In addition, suddenly adding large amounts of electrolytes before or after a competition to a horse that isn’t used to getting them could disturb the hind gut and cause gastrointestinal problems.

Sodium and chloride should be the main ingredients in an electrolyte supplement; check for this when choosing which electrolyte supplement to use. Some electrolyte supplements, such as Pure Plus Electrolyte, use micro-bead technology which means they have a fat coating. This improves efficiency and palatability. It helps to ensure that the electrolytes reach the small intestine to be absorbed, where they can have maximum effect. The fat coating also means that the electrolytes do not irritate the stomach lining; especially beneficial for horses with gastric ulcers. Palatability is improved with fat coated electrolytes as the coating reduces the salty taste. This makes the need for additional sugar to encourage ingestion of the electrolyte redundant and thus makes them suitable to feed to horses that need a low sugar diet.

Electrolytes can be added to the feed, added to water or given as a concentrated paste. If electrolytes are added to water, another source of water without anything added to it should also be available to the horse. The downside to giving electrolytes in water is that it can be difficult to know exactly how much of the electrolytes your horse got from the amount of water that they drank. In all cases when feeding your horse electrolytes, fresh clean water should also be available.

The amount of electrolyte to feed will depend on several factors such as your horse’s breed, duration and intensity of exercise, fitness level, diet, environmental conditions (horses have been shown to sweat more in humid and hot conditions than in cool conditions) and their individual metabolism.

As always, it is important you follow the manufacturer's guidelines and feeding recommendations. If you do, over supplementation of electrolytes is unlikely. However, signs to look out for include excessive drinking and excessive urinating.

Other dietary considerations As well as providing electrolytes, clean, fresh water should always be available to your horse. Ensuring that your horse has plenty of fibre in their diet is also beneficial to help prevent your horse from becoming dehydrated. Fibre helps to trap water in the hind gut, as well as electrolytes, providing a reservoir which can be used when needed.