DISEASES OF THE OSSEOUS STRUCTURES. 169 



CHAPTER IX. 

 Diseases of the Osseous Structures. 



Diseases of bone are arranged under two heads, 'in- 

 flammatory' and 'non-inflammatory,' but the Hue of 

 demarcation between the two is not very well defined. 

 The process of inflammation takes place in bone just the 

 same as it does in the soft tissues. Inflammation of the 

 substance of the bone is termed ' ostitis.' Superficial ostitis 

 is often associated with periostitis, or inflammation of the 

 periosteum. Ostitis may terminate in resolution, or bony 

 enlargements, etc. On making a section of a bone, compact 

 and cancellated tissue is found. The first effect of inflamma- 

 tion of bone is to increase the size of the Haversian canals. 

 More particularly is this the case in connection with the 

 compact tissue. The earthy salts are partially removed, 

 and their place is filled by the products of inflammation. 

 The union between the vascular system and the earthy salts 

 is dissolved, and the Haversian canals become irregular in 

 outline, run into each other, etc. Inflammation of bone in 

 a greater or less degree will cause exostoses, as spavin, 

 splint, etc. Inflammation may be excited by a great many 

 causes, but the most prolific cause of ostitis is injury, either 

 direct or indirect. It may also be produced by a constitu- 

 tional tendency. In joints the articular cartilage very often 

 becomes absorbed, and osseous material is thrown out, pro- 

 ducing anchylosis, which is union of the bones composing 

 the joint, and a stiff or completely immovable joint is the 

 result. 



Another disease of bone is caries (ulceration, or death 

 of the bone in small particles). Caries occurs sometimes 

 as a result of poll-evil, fistulous withers, etc. As a 

 general thing, the veterinarian has in his patients ' dry 

 caries.' A horse may be lame in the hock, and that too for 



