CHAPTER IX. 



DISEASES OP THE BoNES AND ARTICULATIONS — Continued, 



ULCERATION CARIES NECROSIS — CENTRAL AND SUBPERIOSTEAL 



SUPPURATION ABSCESS IN THE SUBSTANCE OF A BONE. 



Writers upon human surgery make a distinction between 

 ■ulceration of bone and caries, both conditions being associated 

 vith the formation of pus. Thus, Professor Syme says — " By 

 ulceration we mean that condition of bone in which there is 

 loss of substance, together with suppuration, but in which the 

 ulcer has a tendency to heal. In caries, on the contrary, while 

 there is a loss of substance, together with suppuration, there is 

 so far from being any tendency to heal, that healing is very diflS- 

 cult to accomplish." The same authority, quoting from Liston, 

 says : — " It may tend to prevent confusion of the two morbid 

 states, if we confine the term ulceration to suppuration in and 

 absorption of bone, whilst the vessels retain a considerable 

 power of action, throw out new matter, and procure a repara- 

 tion of the breach ; and this condition of the osseous tissue 

 exists when the disease is situated on the surface of the bone, 

 and when it has been induced by an external cause. On the 

 contrary, the term caries will denote that particular kind of 

 ulceration in which reparation is hardly attempted by nature, 

 and is with difi&culty obtained by the most active influence, 

 and this disease will be most generally found to affect the 

 cancellated structure. 



To the veterinary pathologist this difference is not at all 

 satisfactory, and it may be laid down as a rule that ulceration 

 of bone with a discharge of pus is the result of external injury — 

 that, in fact, there is necrosis, o?: actual death of a layer of 



