ANIMAL HEAT 381 



body temperature, with increased respirations and pulse, will 

 occur as the result of standing in a hot sun, even though doing 

 no work. This passes away with acclimatisation, but increased 

 respirations on a hot day are always evident even in animals of 

 the country. 



The loss of body heat among animals lying out at night is 

 partly prevented by the fatty covering to the peritoneal cavity, 

 which saves undue conduction of heat. Wet, combined with 

 exposure, causes a more important loss of heat than mere cold. 

 It has been shown from exact observations on man that a limb 

 clothed in wet flannel lost 34-4 per cent, more heat than the same 

 limb in dry flannel. Animals never look so wretchedly miserable 

 as after a night of cold rain ; under the conditions of active service, 

 a cold, wet night is certain to kill off the most debilitated. 



A physiological resistance to cold can be obtained by training ; 

 the body learns to regulate its loss and production of heat, and 

 this brings us to a consideration of the interesting practical point 

 of the necessity of clothing for animals, especially for horses, in 

 a state of domestication. Some animals, such as the horse, ox, 

 and sheep, are born fully developed and clothed ; in a few minutes 

 they pass from a temperature of between 101 to 105 F. within 

 the womb of the parent, to perhaps freezing-point on the bare 

 ground. The power of regulating their temperature is fully 

 established, and in a very short time this is assisted by muscular 

 movements of the limbs, which are learnt very quickly ; the 

 gambols of young animals serve some other purpose than that 

 of mere lightness of heart. If healthy, cold has no effect on 

 these young creatures, provided the parent is able to supply 

 sufficient nourishment. There are other animals, such as newly- 

 born pups, kittens, rabbits, and certain birds, such as pigeons, 

 which are born blind, helpless, and more or less naked ; they 

 cannot move, are unable to regulate their temperature, and if 

 taken from the maternal warmth their body temperature steadily 

 declines and they die from cold. In these the capacity for 

 regulating body temperature does not develop for some little 

 time after birth, and until locomotion becomes possible. 



Effect of Low Temperatures. — -We have seen, then, that 

 the young of the horse comes into the world prepared by its 

 heat-regulating mechanism to deal with the question of external 

 temperature, and as time goes on this is supplemented by an 

 extra growth of hair for winter use and a lighter covering for 

 the summer. If no interference with the coat be practised it is 

 undoubted that no extra covering of any kind is required during 

 the coldest weather, and even where the natural covering is of 

 the lightest, as with the thoroughbred horse, it is sufficient 

 for the purpose. The thoroughbred brood mares of this country, 



