186 PBINOIPLES OF VETEBINABY SUBGEBY 



Name the causes of hone necrosis. 



It is usually the result of a disturbed circulation of the 

 blood caused by (1) traumatism, (2) inflammation. 



How do traumatisTns produce necrosis ? 



Suppose that an animal is kicked and a complicated frac- 

 ture the result. Bony splinters in such a fracture are no 

 longer supplied with nutriment, as their blood supply is inter- 

 rupted. Being a coniplicated fracture — that is, one infected 

 by pus-producing bacteria— these bony fragments become 

 necrotic. In subcutaneous bone wounds, or, for that matter, 

 bone wounds which are not infected — that is, in an aseptic 

 state — small bone splinters will be absorbed. 



How does inflammation produce necrosis 9 



Most commonly necrosis follows infectious inflammatory 

 processes which may either arise in the bone or invade it 

 from adjoining tissues. The former, for instance, are repre*- 

 sented by purulent periostitis and osteomyelitis as seen in the 

 inderdental spaces of horses bitted severely or inclined to 

 pull, or in the latter it reaches the bone by continuity ; for 

 instance, in severe inflammation of the pododerm the os pedis 

 — that is, a portion of it — may undergo necrosis. In severe 

 phlegmonous states of the muscles and f ascise overlying the 

 dorsal vertebrae, as is seen in fistulous withers, some parts of 

 the vertebrae may undergo necrosis, etc. 



What do you understand by caries ? 



The slow death of a part of a bone with softening, solution 

 and partial absorption of the same, almost invariably due to 

 specific infections, especially tubercular osteomyelitis and 

 osteitis. It is a form of necrosis. 



