Brandenburg’s Tidbits | Did you know? @Electrolytes – Your Horse, Exercise, and the Heat

Everyone looks forward to the warm weather as the ideal time to ride/work their horse. Most understand the dangers of working a horse under conditions of high heat and humidity. However, a horse can be compromised easily under less than sweltering conditions if you don’t know how to correctly protect them.

Dehydration through sweat loss is the major danger. As little as a 3% of body weight sweat loss can cause almost a 10% reduction in the horse’s exercise tolerance. For a 500 kg/1100 lb horse, that’s only 15 liters of sweat. Research has shown that a horse sweating heavily can lose as much as 16 liters of sweat in just one hour.

Even at light levels of sweating, horses working in more mild weather conditions or horses on turnout in hot weather that are obviously sweating, sweat loss is around 4 liters per hour.

Obviously, an adequate supply of palatable water is a huge factor in avoiding dehydration. However, water is only part of the answer. For a horse’s body to hold onto the required amount of water, electrolyte levels must be correct.

Sodium, potassium and chloride are the major electrolytes. Bicarbonate is also important but a horse’s body can produce that from carbon dioxide and water as needed, and bicarbonate is not lost in the sweat.


Sodium is the electrolyte that the horse’s body “reads” in the brain to determine whether to send out the impulse to drink more water. If sodium concentration in the blood increases in relation to water, the brain will send out the message to drink.  However, if sodium content in the body is not what it should be to begin with, blood concentration will not increase enough to trigger drinking even if there is a significant reduction in body water (dehydration).


A 500 kg/1100 lb horse loses 20 grams of sodium per day in bodily fluids, not including sweat. This equates to about 1 oz of plain table salt (sodium chloride). A horse standing around and not exercising but under conditions of high heat could need 2 to 3 times more than that just to meet basic losses without even being exercised.

Choose an electrolyte supplement close to a ratio of potassium:sodium:chloride of 1:2:4. Horses getting generous forage can go with lower potassium.

Make sure you provide baseline requirements first, then use an electrolyte supplement as needed to replace sweat loss. This will maximize performance and protect against problems caused by dehydration and electrolyte imbalances.

A few simple steps will keep your horse with better water and electrolyte status in the heat.

  • Do not rely on salt intake from licks. Add directly to meals and/or mix in water and spray on hay.
  • Feed 2 oz of plain salt or an electrolyte supplement low in potassium every day.
  • Always let your horse drink freely and as much as they want during exercise lasting longer than 2 hours and also immediately after stopping work. Research has shown horses who have their access to water restricted while cooling out do not drink as much in total as horses with unrestricted water access.

Choose an electrolyte supplement that has approximately twice as much sodium as potassium and twice as much chloride as sodium.

This is article is borrowed from the Uckele Nutritional Archives.   Written by Dr. Eleanor Kellon, VMD


I just have to start with this short article I found about electrolytes.  Like most of us, I understand the need and purpose of feeding electrolytes to our horses.     But I was surprised to find out that …As little as a 3% of body weight sweat loss can cause almost a 10% reduction in the horse’s exercise tolerance.   Puts it in perspective doesn’t.  Wow, makes you wonder how our horses have accomplished the feats that they have during the hottest summer on record?

More thoughts about maintaining  good hydration levels:

  • I recommend having both Paste and Top Dressed Electrolytes .    You can feed your top dress daily & keep your paste on hand for emergencies or a boost.
  • Its not just offering your horse water.   Its offering fresh, clean water.    Make sure to clean your tank & water buckets regularly.   They do grow some funk in these Über hot conditions.
  • Make sure you provide plenty of fiber to their diet.    High fiber diets can actually assist with maintaining hydration.    So if you have to haul.   Give plenty of  hay, water, & electrolytes to ensure a safe arrival to your destination.
  • Remember your horses need to be given electrolytes even if they are just hanging around the pasture or barn.    Because I promise you, this summer they are sweating even if they are not working & exercising.
  • Offer free choice salt next to your water source as well as adding it to their food consumption.
  • Try to adjust your schedule so that you are exercising your horses at the coolest times of the day possible.   Its better to inconvenience ourselves for a short time than to risk their health.