CARIES. 171 



sary to stimulate the parts ; that is, where thece is only a 

 slightly diseased condition of the bone. In such a case it ' 

 may be sufficient to touch the diseased portions of the bone 

 with dilute hydrochloric acid. If the presence of caries in 

 an articulation be suspected, the treatment should, of course, 

 be different. If it exists in the true hock-joint, a cure can 

 never be effected ; but if in a gliding articulation, the treat- 

 ment consists in hastening the process of anchylosis. 

 Therefore give rest, and try counter-irritation, which sets 

 up a new inflammation. The products of the original in- 

 flammation become organized, converted into osseous 

 material, and the process of union goes gradually on until 

 anchylosis becomes complete and' irritation ceases. The 

 best form of counter-irritation in such a case is that result- 

 ing from the application of the actual cautery, after which 

 the application of vesicants, repeated at proper intervals, 

 ,may be attended with benefit, anchylosis usually becoming 

 complete within a few months. 



NECROSIS. 



Definition. — Death of Bone. Xecrosis is of rare occur- 

 ence in the lower aniaials, and when it does occur in the 

 horse, it is due in a large majority of cases to injury, either 

 directly or indirectl}' received, and is very rarely due to 

 constitutional disturbance. Xecrosis is analogous to gan- 

 grene in the soft tissues. After the bone dies it assumes a 

 very white appearance, and seems to be harder than natural, 

 and finally, becoming exposed to the air, it exfoliates, 

 separates, and comes away. Xecrosis is oftenest seen in 

 connection with the lower jaw, and is due to injury caused 

 by the action of the bit. AYhen a portion of bone dies it 

 must be got rid of in some way ; its removal is effected 

 usually by surgical interference, and sometimes by an effort 

 of nature. 



