anhydrosis

Inability to sweat in response to work output or increases in body temperature. Also known as a "non-sweater." Most are athletic horses though frequently the condition appears in pasteured horses not being ridden. Most commonly occurs when both the temperature and humidity are high. Horses raised in temperate regions and then transported to hot climates are most prone to develop the condition but even acclimated horses can be at risk. Clinical signs include inability to sweat, increased respiratory rate, elevated body temperature and decreased exercise tolerance. The condition can be reversed if the horse is moved to a more temperate climate.