X84 THE DOG IN DISEASE. 



NORMAL TEMPERATURE OP THE DOG. 



The bodily temperature of any animal is the result of 

 that series of chemical processes inseparably associated 

 with life. The fact that the temperature remains, under 

 the most varying circumstances, constant -within narrow 

 limits, is one of the most wonderful examples of adap- 

 tation of complex vital mechanism to environment con- 

 ceivable. 



Physiologists now universally recognize two factors in 

 this equilibrium — heat production and heat dissipation or 

 loss, which in health balance each other. Heat production, 

 as well as heat regulation, is controlled by the nervous sys- 

 tem. Heat is lost chiefly by the skin and lungs, though in 

 a slight degree by the passage of urine and faeces. 



The amount of heat produced in any tissue or organ is 

 dependent on its activity. The muscles are the greatest 

 source of heat, and among glands the liver. The blood is 

 constantly being cooled at the surface of the body and in 

 the lungs, and as constantly being warmed in the deeper 

 muscles and the internal organs. With exercise there is 

 increased metabolism, augmented chemical activity, more 

 heat produced, and the necessity for greater dissipation of 

 heat if the balance is to be maintained ; hence the dog 

 loses heat by his skin and by his lungs to a greater extent, 

 breathing faster and with open mouth. Some animals 

 lose a great amount of heat by sweating ; the dog not so 

 much in this way. 



It is plain that whatever will throw these two pro- 

 cesses out of balance will give rise to a departure 

 from the normal temperature, either in the direction of 



