CHAPTER II. 



DISEASES OE BONE. 



The skeleton of the horse is made up of 242 bones ; and as 

 these bones are the hard framework of the animal body,' 

 serving for the support and attachment of the softer textures 

 and the protection of delicate organs, they are consequently 

 liable to the same accidents and diseases as other parts of 

 the body. They are composed of animal and earthy mat- 

 ters, in the proportion of one- third of the former to two- 

 thirds of the latter. They are covered externally by a sen- 

 sitive and vascular membrane called the periosteum, and 

 lined internally by a similar membrane called the endosteum. 

 They enter into the formation of joints, their ends b^ing 

 held together by the ligaments, and their adjoining surfaces 

 being covered by cartilage or gristle, with a lubricating fluid 

 between, called synovia or joint-oil, to prevent friction, and 

 facilitate the motion of the joint. 



Diseases of bones are not very numerous in the lower 

 animals : the most common are : — Exostosis, in which we have 

 an enlargement or bony tumour thrown out on the surface 

 of the bone ; when between two bones, and uniting them 

 together, it is called Anchylosis Caries, generally defined 

 to be an ulceration or disintegration of the bony texture ; 

 Necrosis, which is the entire death of the whole or part of a 

 bone ; Osteosarcoma, (which is a disease more particularly 



