170 THE PRACTICE OF VETERINARY MEDICINE. 



a considerable length of time, without any external mani- 

 festation, as enlargement, etc., of the hock-joint, being shown. 

 In such a case the articular surfaces of the bones are 

 ulceratinsr. 'Necrosis' is death of a bone. A bone such as 

 the humerus may die and be replaced. A case is on record 

 where a scapula would have been replaced, accidental death 

 of the animal alone preventing it. 



CARIES. 



Definition. — Ulceration, or death of bone in small par- 

 ticles. The vertebrae are oftenest affected, as in poll- 

 evil and fistulous withers. In the extremities, the hock 

 bones, the pastern, and navicular bones are the ones 

 oftenest affected. A dried specimen of carious bone pre- 

 sents a dry, worm-eaten appearance, due to molecular decay, 

 and it is as a general thing unassociated with pus. In the 

 hock-joint caries is associated with spavin, and in the 

 navicular bone with navicular disease. Caries is, of course, 

 sometimes accompanied by a discharge of a very offensive 

 odour, due to the presence of sulphuretted hydrogen. On 

 going to the bottom of a sinus, the presence of a carious 

 bone can be at once detected by the sense of touch. 



Treatment. — The general treatment of caries is somewhat 

 tedious, but in every case the practitioner is to endeavour to 

 bring about a healthy action, and as a rule, the first step in 

 this direction consists in cutting down upon, and exposing 

 the diseased structures. As, for instance, in a case of 

 fistulous withers, the knife should be freely used to divide 

 the soft tissues until the diseased bone is reached, when it 

 should be scraped with the bone-spoon until all carious 

 portions are removed. Where extensive disease exists, 

 scraping with the bone-spoon will rarely suffice, in which 

 case a portion of the bone must be removed by means of 

 the bone-forceps or bone-saw. Sometimes it is only neces- 



