The Importance of Electrolytes and Salt in the Equine Diet

R. Dean Meyer DVM

The last few days have hinted that summer may finally be on the way. When the weather turns hot it is important to remember proper hydration in not only ourselves, but also the equine athlete. Just like humans, horses cool themselves by sweating. Not only is water lost at this time, but also many very important minerals needed for proper body function.

The horses body is about 65% water (1200 lb horse has about 87.5 gallons of water). During steady exercise at a temperature of 60-70 degrees F horses will lose about 1.5 gallons of water per hour. When it is very hot this increases to almost 4 gallons per hour.

Electrolytes regulate fluid exchange between the body's cells and therefore help regulate body temperature, this is especially necessary during strenuous exercise. These minerals help the horse from becoming dehydrated (as long as water is also supplied). Electrolytes also establish proper electrical gradients across cell membranes for proper muscle and nerve function.

What can happen if electrolyte levels are too low? Dehydration, muscle cramping and tying-up, poor nerve and muscle function (fatigue), lowered electrolytes levels can also decrease feed and water intake. When the body looses between 4-5% of water weight (1 hour of hard exercise in hot weather) body temperature will increase at a faster rate leading to possible heatstroke or stroke.

What should be in the electrolytes I use for my horse? There are no hard fast rules, but in general an electrolyte product should contain 25-35% salt, and relative to the amount of sodium should have twice as much chloride and a little less potassium.

How do I know when and if my horse needs an electrolyte? The more the horse sweats the more electrolytes the horse needs. The better balanced the base ration of the feed, the less likely you will need electrolytes for a horse in light work. Horses at maintenance or low levels of work do not generally need electrolytes if they have a balanced diet and are consuming the correct levels of salt (2 oz per day).

Horses in training or competition in high heat and or humidity should receive electrolytes 24 hours before work and continue daily thru the heat and humidity. This includes horses in endurance or 3-day eventing competition or any other strenuous training and work. Make sure that water is available at all times.

Electrolytes can be administered in feed form; salt based which is top-dressed on top of the grain mix. This is usually very palatable with little resistance. This is the ideal form.

Sugar based products which dissolve in water are added to the drinking water. Refusal rate is a factor, beware many of these are high in sugar and have low mineral levels. This can also cause horses to refuse their water source so this can be a real problem. Some people will also mix these forms with applesauce or yogurt, and paste forms are available.

You need to know how much water your horse is consuming per day. Water your horse with a bucket if you are unsure. Horses should consume 10-15 gallons per day with a minimum of 5.5 gallons of water per 1000 lb horse.

Salt is also very important for the horse to ensure adequate water consumption. Horses require 2 oz of salt per day. The horse is a smooth tongued animal. The commercial salt blocks that are commonly made available to horses do not allow them to consume their requirement for salt. These blocks were designed for cattle or other rough tongues livestock. Loose salt is available at most feed suppliers and can easily be top-dressed on the horses feed or be left out free choice for them to consume. Salt blocks can be used but loose salt must also be top-dressed to ensure adequate consumption.

Please call your veterinarian if you have any questions or concerns about your horse's water consumption or the need for electrolytes.