Electrolytes: There’s more to hydration than water.

Dr Jim Rawlinson BVMS MBA MRCVS

After the disruption to exercise, training and competitions this year, we must take extra care as we bring our horses back into fitness for a more active summer. Whatever we are planning, warm weather leads to increased sweating. This means we need to understand electrolytes to help keep our horses healthy and working at their best.

Sweating is the way that our horses lose heat to stay cool in warm weather, especially when exercised. It’s a natural process, so if a horse always has access to water, what’s the problem? They work, have a drink, and replace the lost water. Why should we be worried about electrolytes? The reason is that supporting our hard-working horses is more complicated than just replacing lost water.

When a horse sweats it loses both water and electrolytes. Water loss leads to dehydration which means they can’t function and perform to their best potential. If uncorrected, dehydration will also cause serious problems. As a horse exercising in warm weather can lose 15 litres of water an hour, and early signs of dehydration are subtle and hard to spot, it’s our responsibility to ensure adequate hydration whenever the horse is working. To do this we have to consider electrolytes.

Electrolytes are vital salts like sodium and potassium that are dissolved in all the body fluids, including the blood. They help keep these fluids at the correct concentration which is vital for the horse’s health and to aid performance. In addition, the concentration of sodium in the blood is key to controlling when the horse drinks, known as the “Thirst Stimulus”.

Normally, when the horse loses some water, the blood becomes more concentrated, and this stimulates the horse to drink. During heavy exercise however, sodium is lost at a greater rate than water, so the blood doesn’t become more concentrated, and the thirst stimulus doesn’t kick in. 1 I’ve noted this with my own horse – after a heavy training session, he’ll look at the proffered bucket of water with no interest at all in drinking. This is one key reason why it’s important that electrolyte levels are replaced and maintained. Studies have shown endurance horses supplemented with electrolytes drank twice as much as others in the same group, replacing nearly all the lost water. 2

Alongside sodium’s thirst stimulus, other electrolytes have many important functions in their own right.

  • When sweating, chloride is lost twice as fast as sodium. Falling chloride levels leads to an increase in bicarbonate which in turn causes metabolic alkalosis. If uncorrected this can result in serious problems such as colic.
  • Vital for cell function so needs replacing when lost in sweat.
  • Calcium & Magnesium. Both key for muscle function and therefore performance.

Normal feed and forage does not contain adequate levels of electrolytes to replace those lost through significant sweating. It’s therefore important to consider supplementation that suits the horse’s workload and the weather.

Whatever you and your horse plan this summer, understanding electrolytes will help result in a healthy, and hopefully successful, season.

Nettex has a range of high-quality electrolytes formulated so you can put in place a supplement regime to suit your horse’s management and levels of work. All are peppermint flavoured for palatability, and rapidly absorbed to replace these vital salts.

Nettex Electrolyte Maintenance Liquid can be mixed with feed, diluted in water, or syringed orally into the mouth. The liquid form provides faster absorption so is ideal as a top up during competition as well as regular use. Electrolyte Maintenance Liquid also contains branched chain amino acids to help with muscle fatigue and recovery.

Nettex Electrolyte Syringe Paste Boost is convenient to keep at hand for use before and/or after exertion to assist stamina and performance. Electrolyte Syringe Paste Boost also contains branched chain amino acids so is ideal for competition or travelling to ‘top up’ electrolytes.

To find out more about the Nettex Electrolytes and more tips on keeping your horse performing at its best this summer go to https://www.nettexequine.com/range/electrolytes/

  1. Waller et al 2008, Equine Comp Exer Physiol 4, 149-158
  2. Dusterdieck et al 1999, Electrolyte and glycerol supplementation improve water intake by horses performing a simulated 60K endurance ride. Equine Vet Journal Suplll 18, 418-424


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