Heat exhaustion occurs when a horse’s natural cooling system—primarily sweating—can no longer keep his body temperature in check. Specifically, when a horse’s core temperature reaches 104 to 108 degrees, heat exhaustion sets in and dangerous physiological changes occur. Prolonged exertion in hot, humid conditions is a common cause of heat exhaustion. Humidity keeps sweat from evaporating and, therefore, cooling the horse. Here’s how to help a horse with heat exhaustion.

1. Move the horse into shade.

This can be under a tree, in a barn or even in the shadow of a horse trailer.

2. Douse the horse with the coldest water available. 

Direct application of cold water to the horse is the fastest and most effective method of lowering body temperature. The notion that putting cold water onto hot muscles can cause cramping or laminitis has been debunked, so use as much of the coldest water as you have. Drench the horse, scrape him dry and then repeat. (If you leave the coat dripping wet, the water won’t evaporate quickly enough to provide cooling.)

3. Use any other cooling aid you have on hand.

If you have ice (or can send someone to get some quickly), put packs along the horse’s head and throat, where major blood vessels serving the brain run close to the surface. Standing the horse in front of a fan as you sponge him down will also speed cooling.

An over-heated horse breathes rapidly and may even pant like a dog to dissipate heat. As he cools, his respiratory rate will return to normal.

4. Assess his attitude.

As a horse cools, his general demeanor will perk up. He will seem more interested in his environment, may want to graze or even begin to object to your efforts to cool him. All of these are good signs.

5. Make water available.

Allow the horse to drink as much as he wants. If possible, offer him lukewarm water—it’s a myth that drinking cold water will cause an overheated horse to colic, but he’s likely to drink more if the liquid is tepid. However, do not try to force water intake with syringes, hoses or other artificial means. If water enters a horse’s lungs, he can develop pneumonia.

6. Use electrolytes sparingly.

If you have powdered electrolytes, add a scoop to a bucket of water, but offer plain water also. Avoid giving a horse with heat exhaustion electrolyte paste because these may throw off his metabolic
balance or contribute to dehydration.

7. Do not give your horse any medication.

A dehydrated horse’s kidneys are already taxed, and drugs can push them over the edge to failure.