Sweating is the main process by which horses keep their body temperature stable. Horse sweat is hypertonic, indicating that the salt (electrolyte) concentrations of the sweat are higher than in the horse’s body fluids. This is a wonderful definition, but what does it mean for the horse? It means that the electrolyte level in the horse’s body fluids can be rapidly lost during heavy sweating. The horse’s body constantly monitors the electrolyte levels. When the electrolyte level is high, the horse is stimulated to drink water. Now, think about the situation when the electrolyte levels are low, such as after heavy sweating. Drinking more water will only dilute the electrolyte levels in the body fluid further; not what the horse wants!   That old saying, “You can lead a horse to water, but you can’t make him drink” is a perfect description of this situation…the horse has lost electrolytes from sweating and will not drink in order to avoid diluting the body fluid electrolytes further.   This setup is clearly the beginning of dehydration. There are many quick tests to determine whether a horse is dehydrated; these include:

• Skin pinch test. Pinch a small piece of the skin in the neck or shoulder area. If it stays elevated more than a few seconds, dehydration is possible.
• Appearance of gums. If the gums look dry or reddened, dehydration is possible.
• Check eyes. Dull and glazed eyes may indicate dehydration.
• Capillary refill. Gently press, with one finger, on an area of the gum above the teeth. The area turns very pale. Release. Normal color should return in 1-4 seconds, if not, dehydration is possible
• You can also check for thick lathered sweat, shallow panting and body temperature over 102 degrees F, which are all signs of dehydration.

Severe dehydration is a serious, life threatening situation; call your Vet! For mild to moderate dehydration (hypo hydration), the solution is easy, unlimited water, and electrolyte supplementation.   Apple-A-Day^TM, Orange-A-Day^TM and Electrocharge^TM are great products for just this purpose (and to help prevent dehydration in the first place). A hallmark of feeding your horse Electrocharge^TM or Apple-A-Day^TM is that within a very short period of time, your horse will want a drink of water. If you just led him to the water, you can count on your horse taking that drink!   Think about the physiology of the situation now: body fluid electrolyte levels are rising, and the horse’s body detects this. Now it wants to dilute the body fluids a little, and the easy way to do that is to have a nice drink of water. Clean, fresh water should always be a free choice for your horse.   FAQ: Do horses need electrolytes in the winter? Horses can become dehydrated, even in the winter. Feeding a daily electrolyte supplement and keeping a salt lick and clean fresh water available year round helps promote healthy hydration for your horses!