Understanding Electrolytes


Losing large amounts of heat means horses need to lose a lot of sweat! In hot conditions 10-15 litres of fluid can be lost per hour. This is equivalent to a full bucket of water! Under normal ambient conditions horses can lose 5-7 litres of fluid per hour. This is equivalent to half a bucket of water and still represents a significant loss.
However, it is not just water that is lost, sweat also contains electrolytes. Equine sweat contains a higher concentration of these salts than blood, this means that significant electrolyte losses can occur in addition to water losses.

What are electrolytes?

Cell functions within the body require a well controlled environment, and electrolytes are crucial to maintaining this.
The main electrolytes are Sodium, Chloride, Potassium, Magnesium and Calcium.


Blood sodium concentration provides the ‘Thirst Stimulus’ (see box below). After mild sweating the horse will lose some water and some sodium, this means that the sodium in the blood is more concentrated (salty) making the horse thirsty so he drinks.
After major sweating the horse will lose a lot of water, but even more sodium will be lost. This means that the blood volume and sodium are much reduced, so there will be less blood and it isn’t very salty. The horse will be severely dehydrated, but as sodium is low he won’t be thirsty. Giving electrolytes will make the blood more salty again, correcting the losses and stimulating the horse to drink. This is why electrolyte replacement is so important. Chloride – Chloride is lost in sweat at twice the rate of sodium. When blood chloride levels drop Bicarbonate levels rise to compensate leading to metabolic alkalosis. Metabolic alkalosis binds calcium resulting in colic or thumps. Calf electrolytes have an alkalising agent within them and are therefore not suitable for horses as they can make the metabolic alkalosis worse.


Most potassium is contained within cells and this will be pulled from the cells into the blood to maintain blood levels when potassium is lost in sweat. However this potassium must be replaced after sweating.

Calcium & Magnesium

Both required for muscle function. Intake is usually adequate but replacement is beneficial post sweating to maintain performance.

Do horses sweat differently to humans?

The short answer is yes! If you or I ran a marathon we would start by sweating salty sweat (a lovely thought I know!). However, as the electrolyte levels in our blood dropped our bodies try to conserve electrolytes by making our sweat less salty, so by the end of the marathon your sweat would be watery.
However, horses continue to sweat concentrated, salty sweat no matter how hard or long they exercise. In fact the greater the sweating rate the greater the sodium levels lost. This means that electrolyte replacement is even more important for horses than it is for humans.
Most of us wouldn’t consider doing a hard gym session or a decent run without having something like a Lucozade Sport or Powerade, however we forget that horses need electrolytes too. Many riders will have an electrolyte containing drink after going cross country, but don’t realise that they need to offer the same to their horse!

What else do you need in an electrolyte supplement?

Branched Chain Amino Acids (BCAA’s) have been shown to help assist endurance and to help delay central fatigue. They also promote muscle recovery after exercise. BCAA’s are included in Nettex Electrolyte Maintenance Liquid and Electrolyte Syringe Paste Boost.
Palatability is also really important for an electrolyte supplement to encourage intake and so that horses enjoy being given it. All of the Nettex Electrolyte Range are mint flavoured.

What are the consequences of electrolyte depletion?

  • Poor performance
  • Exhausted horse syndrome
  • Metabolic disturbances
  • Hyperthermia
  • Exertional rhabdomyolysis
  • Thumps
  • Renal failure
  • Colic
  • Collapse
  • Death
  • When to feed electrolytes?
Electrolyte supplements are essential for optimal performance. All sweating horses require an electrolyte supplement. The Nettex Electrolyte Range provides a solution for all situations. Nettex Electrolyte Maintenance Powder and Nettex Electrolyte Maintenance Liquid are ideal for daily maintenance for all horses, with Nettex Electrolyte Liquid also being ideal for easy administration during competition. Nettex Electrolyte Syringe Paste Boost is designed to a ‘Top-up’ for pre, post, or during competition and for use after unexpected sweating, such as after travelling. It can be used in addition to Nettex Electrolyte Maintenance Powder or Liquid to ensure a speedy recovery after strenuous exercise.

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