HEAT EXHAUSTION

► Definition: 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.

► Causes: prolonged exertion in hot, humid conditions. Humidity keeps sweat from evaporating and, therefore, cooling the horse.

► Signs: Respiration increases to between 60 and 80 breaths per minute (compared to the normal 15) when a horse has heat exhaustion, and he will likely stand quietly with his head lowered and seem oblivious to his surroundings. If a fold of skin pinched at the shoulder remains “tented” for more than a few seconds, he may also be dehydrated, a condition that often accompanies heat exhaustion.

In some cases, a horse with heat exhaustion may perspire less than normal or not at all, a potentially confusing sign that indicates his sweating mechanism is shutting down and his temperature will climb even higher if conditions persist.

► Treatment: lowering a horse’s body temperature as quickly as possible, rehydration with intravenous fluid if necessary and supportive care