How to Feed Electrolytes to Horses

We recently had a horse owner ask about providing electrolytes to her horses all at once, through the watering trough.  While in theory this might work, in practicality, it may cause some issues.

First, it is important to understand what horses need:

  • The key electrolytes are sodium, chloride, potassium and magnesium.
  • Forages and feed normally contain adequate potassium and magnesium to maintain body levels.

Then, we need to understand how a horse consumes & utilizes electrolytes:

  • The best way to add these to a horse’s diet is to provide free choice salt in a loose form at all times, as sodium and chloride are the primary electrolytes lost in sweat.
  • Horses may not consume enough salt if the salt is in block form, particularly during cold weather or hot, humid conditions.
  • Horses cannot store excess electrolytes and will excrete in the urine.

If you have particular events where the horses will be worked hard, particularly in hot, humid conditions, it is recommended to provide the additional electrolytes immediately prior to, during and immediately following a competition.  Maintaining water consumption is key to preventing dehydration and adding electrolytes to the water may not be desired.

Dr. Krishona Martinson at the University of Minnesota recently published a useful newsletter review that suggested that adding supplements to the drinking water for horses can actually decrease water consumption, which is exactly what you would want to avoid doing.

Warm Temps & Water Consumption

The transition in temperature and humidity from cool season to warm season may require an adjustment in watering horses. Reduced water consumption may impair performance and may increase the risk of impaction colic. Also, horses that are not conditioned properly may sweat more profusely than a well-conditioned horse, and thus dehydrate faster. This is particularly important early in the season when temperatures may change suddenly and horses may not yet be in peak condition.

The first key element is to make certain that horses have ready access to clean, palatable, cool water at all times or at very frequent intervals. Horses will normally consume about 1 gallon of water per 100 lbs body weight, so an 1100 lb horse will require a minimum of 11 gallons of water per day. This quantity can increase substantially during periods of exercise, high heat/humidity or for lactating mares.

Some tips to keep in mind to keep water consumption up:

  • Horses do not like to consume warm water in warm temperatures. Automatic waterers or large tanks, located in the shade and cleaned regularly, may be good options. If water is supplied in buckets, they need to be cleaned regularly and re-filled regularly.
  • If you are traveling to a show or other competition, it is essential to monitor water consumption, particularly if temperature conditions change.
  • It is routine in many barns to flavor the water with something like wintergreen or peppermint at home so that you can flavor the water in new facilities to match the home water.  Read here for tips on training your horse to drink water away from home.
  • Do NOT use soft drinks or any material containing caffeine as these can trigger positive drug tests.
  • Taking horses to facilities with chlorinated water can sometimes reduce water consumption without proper precautions.

The second key element is to make certain that salt is offered free choice. Things to keep in mind for salt consumption in horses include:

  • Horses require 1-2 ounces of salt per day, and this can increase to 6 ounces per day with exercise in hot weather conditions.
  • Loose salt is consumed more readily than salt blocks in many cases.
  • When evaluating the total diet for salt consumption, commercial feeds normally contain 0.5-1.0% salt. It is not typically any higher than this, due to problems with palatability.
  • If a horse has been salt deficient or is bored, they may over-consume salt while in a stall.
  • Additional electrolytes, commercial or personal recipe, may be used per directions before, during and following completion, but care must be taken to ensure that the horses are drinking adequate water. Administering electrolytes to a horse that is not drinking properly, or allowing a horse to over consume salt without adequate water, can lead to electrolyte imbalances. If electrolytes are added to the water, plain water should be offered also.

Horses need to be offered water throughout the day at a competition, and should be re-hydrated following exertion. They cannot cool out and recover properly without being re-hydrated. Keeping horses properly hydrated and maintaining electrolyte balance is extremely important in order to make a safe transition from cool temperatures to summer time and competition.

Feeding Horses During Hot Weather

Performance horses in all disciplines, from racing to western pleasure, are expected to deliver optimum performance all year around, regardless of temperature. Summer conditions of high temperature and humidity presents several challenges to the horse owner. Proper management of working conditions, water consumption and feeding practices can help meet the challenge.

Working Conditions:

  1. Early morning and evening rides are better for both horse and rider.
  2. Horses confined during the day should have shade, ventilation and fresh clean water. This applies to horses in stalls, at shows or in the pasture.
  3. If horses must be trained or shown during the heat of the day, they should be offered water regularly. A hot horse should not be allowed to drink large quantities of cold water then stand, but a horse cannot cool down properly if it is dehydrated. The rule “six sips and walk” provides a good guideline. Horses going in classes throughout the day must be allowed to drink regularly, as dehydration and heat stroke can be deadly.
  4. Loss of fluid can also make a horse prone to colic. If a horse stops sweating, immediate action is required.

Feeding Management Practices:

  1. Adjust the energy sources fed. The horse’s total thermal load can be reduced by using highly digestible fiber sources and added fat feed sources.
    1. High fiber hay produces more heat increment or heat of digestion than lower fiber hay.
    2. Fat produces the lowest heat increment.
    3. The most heat efficient hay source for a performance horse would be an early cut grass or grass legume mixture. This hay should be fine in texture and relatively soft to the touch.
  2. An added fat feed or the addition of corn oil to the diet will provide higher energy with lower intake, and will assist in reducing the thermal load. Added fat diets may also produce the additional performance benefits of increased endurance and reduced fluid loss.
  3. Feeding small amounts throughout the day rather than two large feedings may also be beneficial as the heat produced by digestion can be spread out.
  4. Very high levels of protein should be avoided as the excess nitrogen increases fluid loss due to the higher urine output.

Feeding Salt & Electrolytes:

  1. Loose trace mineral salt in a feeder protected from rain should be available free choice. Manufactured feeds will generally contain 0.5%-1.0% salt, but a performance horse may require 4-6 ounces of salt per day to maintain electrolyte balance. Horses will generally not consume this much block salt.
  2. Electrolyte supplements may be beneficial immediately before and during a competition, but care must be exercised to make certain the horse is consuming adequate water.
    1. Giving a concentrated electrolyte without adequate water consumption may actually increase the potential for a problem.

Summer is a great season to spend more time with horses. Proper management can help make certain it is pleasant and safe for both horse and rider.