360 AMERICAN FARMER'S HORSE BOOK. 



come overheated by local or general irritation in the system. 

 Some part is cut, bruised, or injured in some way; some lesion 

 of muscles, tendon, or membrane has taken place; some 

 bone is broken or nerve impaired; some dreadful exposure 

 to cold has made the whole body sore; in some way, and 

 from some cause or other, a certain organ or part has re- 

 ceived injury, so that it is weaker, more frail than the others. 

 It suffers increasingly from this injury, and becomes more 

 sore ; irritation and heat are here augmented, and fever arises. 

 The most familiar sources of heat are combustion and fric- 

 tion. Animal heat is principally evolved by a process essen- 

 tially the same as the former, while it is the latter which 

 generates fever. Fever heat is the result of the friction of 

 the blood, surcharged with the heat fcpm the injured and, 

 presently, inflamed part. It is not that the blood heats the 

 part, or even itself, but that the inflamed and heated part 

 heats and inflames the blood. 



It is a principle laid down in Chapter I of this work, 

 among the important facts to be remembered in treating dis- 

 eases of the horse, that nearly all disorders of both man and 

 beast, whatever may have been the primary or external 

 causes, proceed from obstruction and derangement of the cir- 

 culatory and secretive functions. Such obstructions are nearly 

 or quite always caused by injuries of some kind. These may 

 be local or general, but wherever they produce obstruction, 

 there will heat and fever be found. 



The shoulder is sprained or bruised, and a tumor arises, 

 marked, by swelling and great heat. From whence comes 

 this increased amount of heat? Certainly not from the blood. 

 Had not the part been injured, the blood would have kept 

 on flowing, as it had been doing from the moment of birth, 

 without the development of any extra heat. This must 

 clearly have its origin in the obstruction. Some of the 

 blood-vessels and many of the little capillaries have been in- 

 jured, or perhaps even broken, and their contents are now 

 discharged into the surrounding tissues. Here begins ob- 

 struction, interruption of the circulation. 



