Evaporative Heat Loss

Abstract

Under hot conditions the amount of heat that can be lost through sensible channels is limited. Moreover, when the dry bulb temperature and the radiant temperature are above body temperature there is a net gain of heat. Evaporative heat loss therefore becomes progressively more important for the maintenance of body temperature as the ambient temperature rises. The vaporization of water from the body may take place (1) from the respiratory tract, where the rate may be increased in panting animals and (2) from the surface of the skin, where the loss falls into three categories: (a) water lost by diffusion through the skin and not subject to physiological control; (b) sweating from special glands, which is under physiological control; or (c) evaporation of moisture derived either from saliva or urine applied to the body surface by the animal or from wallowing in mud and water.