Prevent Horse Dehydration

Horses are more susceptible to dehydration than other animals. Because they have significant muscle mass, they generate a tremendous amount of muscle heat and sweat profusely when worked hard in warm temperatures. This causes your horse to lose body fluids and the ionized minerals (electrolytes) that they contain.

Your horse usually sweats in an attempt to cool himself. When faced with the choice of overheating or dehydrating, the body chooses to dehydrate, using up water to keep cool. But there is a limit to the horse’s water reserves, and as he begins to run out of body fluid, his temperature climbs.

A dehydrated horse without sufficient fluid to stay cool may suffer a 3 degree increase in temperature per hour of moderate exercise.

Your horse can lose up to four gallons of fluid per hour when he works hard in hot weather. If the air is dry, sweat evaporates quickly and cools the horse. But if the air is humid, sweat won’t evaporate. Your horse stays hot and clammy and sweats even more in an attempt to cool off.

Check for these common symptoms of horse dehydration:

Pull out a pinch of skin on your horse’s neck or shoulder. If it springs right back into place, he’s not very dehydrated. If he is moderately dehydrated, the skin will stay elevated a few seconds after you pull it out. The more dehydrated he is, the longer the skin will stay elevated.

Dry, red mucous membranes inside the nose and mouth.

Dry, muddy colored gums.

Membrane under the horse's eyelid should be pink to pink-yellow. Red indicates stress. Brick red indicates severe stress. Blue membranes indicate a critical situation.

Capillary refill time will decrease. Press your finger into your horse's gums just above his front teeth. The gum will turn white because you've pressed the blood out. Normal color should return within one to four seconds. The longer the refill time, the more dehydrated your horse.

Dull, glazed eyes and wrinkled eyelids.

Thick, lathered sweat.

Increased temperature (over 102) that doesn't return to normal after exertion. Learn the safest way to take your horse's temperature here.

Shallow panting, muscle tremors and weakness, weak pulse, depressed attitude.

Horse dehydration can also trigger muscle cramps (tying up or horse colic) since fluid and electrolytes necessary for proper muscle function are depleted.

Prevention:

Condition the horse before hard rides.
Clip the coat.
Provide balanced equine electrolyte supplements as a part of regular nutrition.
Water frequently.
Frequently cool the horse with water to reduce the need for sweating, but avoid rapidly cooling large muscle areas.

Treatment:

Get the horse into shade. Cool with a fan if possible. You can also cool with water, again avoiding large muscle areas.

Moderate dehydration can be reversed by giving the horse all the water he will drink, and allowing him some free-choice electrolyte powder with his feed or dissolved in his water.

Severe and dangerous dehydration can best be reversed by giving electrolyte fluid intravenously. Fluid by stomach tube or into the rectum (where it is readily absorbed) can be helpful, but a severely dehydrated horse will need lots of intravenous fluid, and veterinary attention.

The stressed and dehydrated horse may not feel like eating. If he has some appetite, that's great. Give him green grass (pasture, not clippings) which is 50 to 90 percent water. Dry hay is only 5 to 8 percent water. The more you can increase your horse's water consumption, the better.

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