Plasma Cortisol levels have been shown to increase during exposure to high temperatures (Collins, Few, Forward and Giec 1969). Growth hormone has been shown to increase (Okada, Matsuoka and Kumahara 1972) or to decrease (Mueller, Chen, Dibbet, Chen and Meites 1974). We have previously found a decrease in serum glucose levels during heat exposure in dogs (Krausz, Marder and Eylath 1977, 1978) and were interested in following glucose and hormo