Signs & Symptoms of Dehydration in Horses

Long periods of low, intense exercise, such as that experienced by long-distance endurance horses on a 25- to 50-mile trek, cause the greatest risk for dehydration to equine athletes, says Dr. Michael Lindinger of the University of Guelph in Ontario on the HorseTalk website. Performance horses sweat at a rate more than four times that of humans, leaving them vulnerable to the dehydration, heat strain and electrolyte imbalances that can result in muscle disorders and collapse. Successful horseback riders know how to prevent their mounts from becoming overheated and dehydrated and learn what signs and symptoms to watch for.

  1. Skin Tenting

    • Veterinarians measure dehydration in terms of the percentage of body weight the horse has lost during exertion or starvation. At approximately 5 percent dehydration, the animal's skin will begin tenting, report veterinarians at Tuft's Cummings School of Veterinary Medicine. This means that if you pull up a loose fold of skin on the horse's neck or withers, it "tents,"creating a v-shape that does not automatically spring back into place. The more dehydrated the horse, the longer the skin stays tented.

    Capillary Refill

    • "Capillary refill" refers to the time allotted for the blood to return through the capillaries to a horse's mucous membranes after they have been compressed. Normally, if you press your finger into the area above the horse's teeth, the gums blanch white. They return to their normal pink color in approximately two seconds. The gums of a dehydrated horse remain pale and tacky. The greater the percentage of dehydration, the longer the capillary refill time, advises the Practical Horsekeeping website.

    Other Signs

    • Other signs of a dehydrated horse include a thick, lathered sweat, excessive panting and a high temperature over 102 degrees Fahrenheit. A horse's normal temperature is 99 to 101 degrees. They may also present with wrinkled eyelids and dull, glazed eyes. Veterinarian Karen Coumbe warns on the Horse and Hound website that severely dehydrated horses suffer from a weak, fast pulse, dark red, tacky gums and cool extremities. Her article also alerts horse owners that some ailing animals sweat less than normal horses due to the loss of body fluids and electrolytes, and it may be hard for owners to tell if their horse is in trouble.