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.

Feeding Electrolytes to Horses

As a follow-up to our recent post on providing adequate water for horses, the following information should be helpful in understanding the use of supplemental electrolytes for horses.  There are a wide range of practices and opinions within this topic, so here are some basic guidelines to keep in mind:

  1. Provide loose salt free choice at all times to all horses.  If loose salt is provided, horses will usually consume the right amount to meet their electrolyte requirements without having to use an additional supplement. 
  2. Horses administered any form of electrolytes need to be consuming adequate water.
  3. Electrolytes should never be force fed to a dehydrated horse, and any horses supplemented with electrolytes should be monitored for dehydration (skin pinch test, mucous membrane color and hydration, capillary refill).
  4. Electrolytes can be used to encourage drinking (e.g. during transport or if horse doesn’t like to drink away from home).  Usually thirst/drinking is stimulated within 3-4 hours after dosing. 
  5. In cases where horses are working extremely hard and losing electrolytes through substantial sweating, a supplemental electrolyte in addition to the salt may be beneficial. 
    1. If heavy sweating due to competition is anticipated, administer electrolytes 1-2 days prior to competition, during the competition and 1-2 days after a competition. 
    2. Doses are usually within the 1 – 4 oz range, depending on sweat loss and the heat and humidity levels. 
    3. A general rule of thumb is usually 30 – 90 g per hour of strenuous work, or follow manufacturer’s instructions if using a commercial product. 
  6. An oral dose (paste/syringe) is recommended over top dress or adding to water, as these methods can create palatability issues and can result in feed/water refusal.
  7. Many commercial products have more sugar that electrolytes in them, so buying a commercial product where sugar is not listed as one of the main ingredients is very important.  Potassium, sodium, chloride, and calcium are the most important electrolytes.