DISEASES OF BONES. 291 



periosteum. In this case partial necrosis generally supervenes. No 

 distinct line or marfrin can be drawn between a canous and a sound part. 

 They glide insensibly into each other. It is remarkable that in canes 

 Nature makes no effort to supply the place of the part which perishes. 



577. Treatvient of Caries. 



Caries when fairly established, may be said to be practically incurable. 

 Bone affected by this disease is never restored to its former state. The 

 object of treatment is rather to arrest the progress of an incipient attack, 

 than to attempt a cure. 



Having regard to the origin of the disease in want of nutrition of the 

 tissue affected, liberal feeding, with tonics, and attention to the general 

 health, are obviously of primary importance. The part ought to be 

 washed frequently by means of a syringe with warm water, to which may 

 be added a disinfecting lotion, or dilute nitric acid or the actual cautery 

 may be applied. 



If these measures fail in arresting the progress of the disease, it will 

 hardly be worth while to go to the expense of further treatment, as 

 restoration of the part cannot be expected. The animal had better be 

 got rid of. 



578. Necrosis. 



Necrosis is death of a bone, or portion of a bone en masse. Caries, on 

 the other hand, is death by gradual decay and absorption of the particles 

 of the structure. Again, necrosis, unlike caries, usually occurs in the 

 Compact tissue. 



This disease is often a consequence of inflammation of the bone, which, 

 as the reader is aware, may arise from very many causes. Among other 

 common causes are severe injuries, excessive j^ressure, contusions, &c. 

 It may also arise from any causes which affect the duo nutrition of 

 bone, such as the removal of its periosteum, or from general debility of 

 the system. 



Necrosis is particularly distinguished from caries, by the endeavour 

 which Nature makes to supply the place of thie portion which has 

 perished. The periosteum, and healthy structures round the dead lx)ne 

 effuse lymph. This ossifies, and forms a ease over the necrosed part. The 

 new bone is therefore always larger, and it is also more spongy in texture, 

 than the original bone. The articular extremities are usually unaffected. 



The old bone though dead, is not removed imtil the new is formed. 

 This is a merciful provision of Nature. The duty of the Veterinary 

 surgeon is to support the strength of the animal whilst the reparative 

 process is going on, and at the proper time to assist in the removal of 

 the necrosed bone. If on introducing through the cloacae, a probe or 

 two probes, one in each hand, a piece of bone is found to be quite loose 

 and separate, it may be removed by the forceps ; or it may be necessary, 

 before removing it, to divide it with a bone-cutting forceps into several 

 pieces, or perhaps to enlarge the opening. Great care and gentleness 



