The Vascularity and Possible Thermoregulatory Function of the Horns in Goats

Abstract

The goat horn is shown to be richly vascular. Heat stress, exercise or blocking the nerves supplying the horn causes vasodilation within the horn, while placing the goat in a cold environment causes vasoconstriction. An inverse relationship between heat loss/min. /sq cm of horn and the ambient temperature allows the heat loss of a vaso- dilated goat horn to be calculated with a good degree of certainty. The resting goat, with average horns, loses about 3% of its heat production through its horns at 30[degree] C in a wind. The same goat would lose 4% of its heat production while running at 0[degree]C in a wind and 12% after it stops running until its horns vasoconstrict. The drainage of cool blood from the horn through the cavernous sinus brings it into close contact with the majority of arterial blood supplying the brain as it passes through the carotid rete. Experiments are reported which indicate that the horn heat loss may selectively control the temperature of the brain.