Excessive sweating occurs with rise of external or body temperature, and this is the so-calledthermoregulatory sweating, which is produced in one of two ways: (a) by the increased temperature directly affecting the heat center in the anterior hypothalamus, or (b) by a reflex from the stimulated nerve endings of the skin, which are not necessarily those which transmit the sensation of heat. The afferent nerve fibers which produce vasodilatation in an overheated extremity travel through the sympathetics; reflex sweating induced by heating a sympathectomized extremity cannot be obtained in a contralateral extremity except after a lag of 20-30 minutes; this is not reflex but is the result of indirect heating due to return of warm blood to the heat center. Emotional sweatingis limited to the palms, soles, and axillae, although generalized sweating may occur, especially in a warm environment. Horses sweat in the