Your Sweating Horse

Horses sweat. And they breathe hard after heavy exercise. That’s normal. However, you should know when these symptoms indicate a problem and what to do about it, including supplementing electrolytes. Download a PDF of this article.

Work in the hot summer sun can use up electrolytes quickly.


A horse’s normal sweat will generally be clear, not lathered (except between the hind legs where it’s commonly lathered or under a girth or breastplate). An exception to this rule would be a truly tough workout, such as a three-day-event cross-country run or a race.

The hard-working horse’s breathing rate will be increased, but the normal horse will recover as he walks out. Offer him water as you cool him out, without letting him over drink. Continue to walk him till he’s cool. If your horse is overly hot, cold-water hose him off, scrape the water off quickly – it quickly heats up on his hot body – and then reapply more cold water. Continue this until he cools. (Cold water will not cause muscle cramps or colic in a normal horse.)

If you’re indoors, you can put a fan on your horse, and if outdoors, get him into the shade. (Do not cover him with a cooler or anti-sweat sheet, as these just make him warmer.)

Track recovery by watching for urination and following respiration rates (write them down, as it will be helpful to the vet if you need help). With severe overheating problems, your veterinarian will need to take blood samples to check the horse’s electrolyte levels.

If your horse regularly works hard, using an electrolyte supplement may be a good idea. You should ensure that your horse is consuming adequate salt, a basic “electrolyte,” as well, as salt consumption is of the utmost importance. (See story on salt.)


Equine sweat differs from human sweat. Our sweat has a high percentage of water. This stimulates us to drink, and we restore the balance of our systems. Horse sweat has a higher percentage of electrolytes, especially sodium, potassium and chloride. And it’s the horse’s salt intake that makes him drink.

Horse sweat is closer to blood composition or “isotonic.” A horse can, with prolonged heavy sweating, change his electrolyte balance and may need veterinarian-administered IV fluids to restore balance.

An electrolyte imbalance can result in thumps, a flutter of the horse’s sides and diaphragm. It may also cause tying up, aka rhabdomyolysis, colic, weakness and heart arrhythmias. If you suspect any of these problems, call your vet immediately.

NOTE: Worse than lathered sweating is the absence of sweating. These horses are generally severely dehydrated and need IV fluids. If your horse never sweats, he may have anhidrosis, a serious chronic condition that can come on suddenly. Call your vet. 


Maintaining electrolyte concentrations plays a major role in keeping the body properly hydrated and healthy.

Electrolytes are minerals that exist in the body in their free, “ionized” form. Ionized means these minerals carry an electrical charge. Minerals with an electrical charge hold water. Sodium and chloride are the major electrolytes in blood and the tissues surrounding the cells. Potassium is the major electrolyte inside cells.

Electrolytes are excreted in sweat, saliva, digestive fluids and urine. All this is normal, and average non-sweat losses every day for an 1,100-lb. horse are:

  • Sodium 10 grams
  • Potassium 25 grams
  • Chloride 40 grams.

However, the harder the horse works, the more he will use through sweat.

Most horses replace these electrolytes through their basic diet and supplemented salt. However, they can run short when the horse’s body tries to make up for heavy electrolyte losses with just salt.

If your horse is working more than 2 hours/day, or at a work level that produces heavy sweating, you’ll want to begin using an electrolyte supplement because your horse may be losing more potassium and chloride than the horse’s diet can provide. Again, this is in addition to the plain white salt.

Replacing lost electrolytes is certainly an understandable method of supplementing, but it will do your horse the most good if you supplement both prior to and after hard works.

When choosing a commercial product, focus on the label’s sodium, potassium and chloride levels. A good supplement will provide around 7 grams of sodium, 3.5 to 4 grams of potassium and 14 to 15 grams of chloride per ounce. Small amounts (less than 1 gram) of calcium and magnesium are also desirable.

Read the label instructions, of course, but as a general rule of thumb, you can provide 1.5 to 2 ounces of the supplement for every hour worked above the 2-hour mark.


For horses in work in hot weather, think “2” to help you remember what to offer:

  • 2 ounces of plain salt the night before work.
  • 2 ounces of plain salt the morning of the work day.
  • 2 or more hours of work per day in the heat, add 2 ounces of a balanced electrolyte supplement for every hour worked over the 2 hours mark.

When choosing a commercial electrolyte supplement, we look for products with ingredient levels that most closely match the electrolyte levels found in sweat, as stated earlier in the article.

Our favorite electrolytes are:


Summer Games


Perfect Balance Electrolytes

Su-Per Lytes.