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Extension by Amy McLean

Written by Amy McLean
Preventing Dehydration in Horses

    There are five main nutrients that a horse needs in order to survive, water, energy, protein, vitamins and minerals.
    Water is the most important nutrient for equine. Most equine can survive a week or two without food but they can only go a few days without water. A horse’s body is approximately 60 to 70 percent water, and a foal is close to 80 percent. During the summer months when horses are worked more readily and sweating more often, water consumption and needs may increase.
    The amount of water required by a horse depends on several factors including but not limited to size, age, body condition score, diet, amount of work and the outside temperature. A fat horse generally requires less water than a horse that is more muscular as fat is generally lower in water content compared to muscle.
    The diet of the horse may also affect the amount of water a horse must consume on a daily basis. A horse consuming primarily a hay diet may have a need for additional water as well as a horse on a high protein diet, but a horse grazing on pasture may require less as grass is generally high in water content. Water is essential for digestion. Horses will typically drink between eight to 12 gallons (27 to 30 liters) of water per day. Most consumption will take place within three hours after consuming a meal. A 1,000 pound horse in a hot environment performing work may require up to 15 gallons of water a day, but only eight to 10 if not performing work.
    Also, consider offering a source of salt to your horse during hot summer months. When a horse sweats, not only does it lose water, it also loses salt and electrolytes. When a horse sweats it loses minerals/electrolytes such as sodium, chloride and potassium. Electrolytes are essential for your horse to maintain homeostasis within its body. Loss of electrolytes and water creates an osmotic response in the blood, thus creating a thirst sensation. Supplying salt and or electrolyte supplements is also of major importance.
    Always provide clean, fresh water to your horse. If you are traveling for several hours, stop and allow your horse to drink. Some horses will not drink water from other areas, so consider adding a flavor to the water to encourage your horse to drink.
    Also, supply a salt and/or mineral block to your horse. When traveling or competing, consider bringing or purchasing a small block. You can also add a few tablespoons of salt to their grain, but make sure adequate water is available when doing this.
    If you suspect your horse is dehydrated offer clean, cool and fresh water. If you still suspect your horse is dehydrated and not performing or looking well call your veterinarian immediately so fluids can be administered.
    Here’s a few tips to check for dehydration in horses:
    -Watch the amount of water being consumed on a daily basis, which is easy to do if you are providing water to your horse by a bucket.
    -Evaluate your horse’s manure. A hydrated horse will have moist manure, but one that may have depressed water intake will have firm manure with less water content
    -Gently apply pressure to the upper lip of your horse, and the color should change from a moist pink to white. Within two or three seconds it should return to the normal color. If not, this maybe a sign of dehydration
    -Use the skin tent test by gently pinching the skin in the neck of the horse. It should fall back to the neck within two to three seconds. If the skin tent is prolonged, this may be another sign a horse is dehydrated.
    Amy McLean is the UW Extension Equine Specialist and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..