February 19, 2020 3 min read

By adding salt to your horse's diet daily, you will avoid dehydration, poor performance and colic. It's cheap insurance!

Electrolyte balance - critical to performance and life itself.

With the warmer weather upon us, it's important to think about electrolyte balance.

  • Is your horse a bit flat?
  • Hitting a wall during a workout?
  • Lethargic and dull?

Getting the electrolytes in balance can make a huge difference to your horses' performance and general wellbeing, it could even save their life!

Like humans, a horses major cooling system is via sweating but equine sweat is much higher in electrolytes than human sweat, and the major ones lost in sweat are sodium and chloride, which together make salt. A horse who sweats lightly during an hour of work doubles the sodium requirement if heavily sweating the sodium requirement can jump up by 500%!

The horse's body performs many of its essential functions by maintaining a gradient between the concentration of sodium outside verses inside the cells. These electrolyte fluctuations are involved with many bodily functions including muscle, brain and heart function as well as the absorption of nutrients in the gut. Sodium and chloride are also the main electrolytes in blood and extracellular fluid. If sodium is low then the cells cannot hold normal levels of water and the kidneys cannot conserve water.

This is what happens when a horse is dehydrated and begins well before outward signs like the skin pinch test can tell you anything about hydration status.

The first sign will be a reduction in performance as well as muscle cramping, possibly a reduction in gut mobility and colic, then the horse may ‘hit the wall’ energy-wise. The horse may show muscular weakness and deranged neurological function.

Dehydration is also a risk factor for Impaction Colic. The most important part of avoiding impaction is keeping the horse and his intestinal contents well hydrated so we need to ensure that the electrolyte balance is maintained.

So how much Salt should you add?

Let's look at Output vs Input to see how much we need to add:


The horse loses electrolytes daily into the urine and manure therefore its essential to supplement a ‘Base Level’ of electrolytes every day. Then increase this amount for sweat losses.

Loses in sweat will be determined by the amount of work and the temperature. Sometimes on very hot days in Australia, it's not uncommon for horses to be lightly sweating throughout the whole day. An anxious horse will also sweat, some very heavily! I know my mare Missy drips with sweat when being trailered or when having her teeth done for example.


When looking at the average Horses diet, it is commonly low in Sodium, closely followed by Chloride. Grass and hay tends to be high in potassium so this is less commonly needed.

A good baseline level of sodium supplementation for an average 500kg horse would be around 10g/day, the equivalent of about 25g of salt.

For every hour of moderate sweating the horse will need another 10g of sodium or 25g of salt. This can increase to 100g of salt for extremely heavy sweating.

If the horse is sweating for more than 2 hours, or sweating very heavily, then you may need to look at using a more balanced electrolyte supplement to make sure that potassium is covered as well, the best ratio for this is 2:1:4 for sodium:potassium:chloride.

Making sure water is available to the horse before, during and after work is very important. Also the timing of feeding electrolytes, if you give them too long before work they will just be excreted in the urine. The first hours' dose can be given within 30 minutes of starting exercise and the rest during or after exercise.

Plain white salt is cheap and easy to supplement, most horses accept a few tablespoons in a damp feed very well.

So in summary

The average 500kg horse will do well with:

  • 2 tablespoons/day as a baseline
  • 2 extra tablespoons for every hour of moderate sweating or on very hot days

If your horse has more than 2 hours of sweating or heavy sweating look at a commercial electrolyte supplement.

It's always best to feed the salt in with the daily dose of minerals to ensure the horse is getting what he or she needs. If you rely on a salt block then the intake may not meet the horses' needs. If you decide to use a block weigh it before and then after 2 weeks of use and calculate what your horses needs are vs how much salt has been ingested. This will give you an idea if the right amount is being eaten.

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