lO • BOARD OF A(mi CULTURE. 



In Necrosis a portion of bone dies, which is called a sequestrum^ 

 and is snrrounded by livhig or germinal matter that will sup- 

 ply the place of this diseased portion when it shall have been 

 removed by carious ulceration or by a surgical operation. 

 Fortunately necrosis is a rare disease in tlie equine system, 

 though very common, as we have before observed, in man. It 

 presents a solitary example of an effort on the part of nature 

 to counteract or provide against the ravages of disease. In 

 this respect it becomes a very interesting subject of inquiry. 



Exostosis is the principal disease in tlie third class that we 

 shall attempt to describe on this occasion. And of all the 

 organic maladies of the horse, this is, by far, the most com- 

 mon and the one, in view of cure, tlie most dreaded by the 

 veterinarian. In its origin it is eitlier acute or hereditary, 

 and in both cases may be transmitted from generation to gen- 

 eration with increasing severity, and thus ultimately ruin the 

 entire family stock. 



By the term Exostosis we mean an extra bony growth, -or 

 tumor, which necessarily involves the periosteum or the cover- 

 ing of the bone. In this respect we shall radically diifer from 

 the views of Dr. Porter, who claims (in his article on the 

 pathological conditions of bone, in the Cyclopaedia of Anatomy 

 and Physiology) that the periosteum is not affected in this 

 disease, but we will not stop to discuss the matter here, for 

 an appeal to the facts concerning its genesis will satisfy even 

 the doubting mind of every earnest inquirer. In a case of 

 acute exostosis, or where it is primarily developed without 

 any hereditary predisposition on the part of the immediate 

 parentage ; this disease usually occurs as the result of an in- 

 jury, either from a blow or a strain. An inflammation follows 

 and an extra quantity of blood, laden with salts of lime, is 

 brought to the part, and thus the periosteum and the surround- 

 ing tissues is thoroughly congested. Eventually the phos- 

 pliate and car'uonate of lime becomes deposited within the 

 periosteum at the seat of injury, and a hard, unyielding, 

 bony tumor is the inevitable result. In fact, ringbone^ splint, 

 and spavin are only different names of the result of this same 

 morbid process of bony growth. All of these affections may 



