RING-BONE. 879 



on the ligaments. Peters says the process begins at the middle of 

 the dorsal or anterior surface of the joint as an inflammation of 

 the capsular ligament. Percival believes, on the other hand, that 

 upright pasterns favour formation of ring-bones, because of the 

 greater shock to which the bones are subject in moving. The abnormal 

 formation above noted is, however, of more importance. The 

 predisposition to ring-bone in young animals is a result of the greater 

 vulnerability of the bones and joints. 



The external causes are sprains and all influences favouring sprain, 

 such as defective formation of the limb, unequal paring of the hoof, 

 using young animals at a rapid pace and on rough ground. Unskilful 

 shoeing plays an important part. If one side of the foot-wall is 

 left higher than the other, that side will first come in contact with 

 the ground, the weight will be distributed unequally in the joints, 

 and the external ligaments of the opposite side may be strained. 

 The " camber " of modern roads acts in the same way. Low heels 

 and long toes are almost always active causes. Heavy horses in 

 mounting hills bring about a similar condition of things ; the leverage 

 of the toe becomes greater. If the general direction of the phalanges 

 (phalangeal axis) be not parallel with that of the walls of the hoof 

 (hoof axis), but more upright, there is danger of straining, not only 

 the different portions of the inferior sesamoid ligaments and the 

 lateral ligaments, but the tendon of the flexor pedis also. Such 

 strain also results when the heels of the shoes become worn down ; 

 and animals with upright pasterns and narrow heels seem particu- 

 larly predisposed. Gutenacker has recently studied it carefully, and 

 has found osteophytes at the points of insertion of the ligaments 

 into the os suffraginis. The causes of rachitic ring-bone are little 

 understood, and the same is true of the reported cases of ring-bone 

 following strangles, and its greater frequency in certain breeds. It 

 has not yet been shown that it is due to deficiency of calcium salts. 

 Traumatic ring-bone is produced by inflammation extending from 

 neighbouring parts to the periosteum. 



Symptoms. The common basis of these conditions is chronic 

 enlargement around the coronet-joint, which is sometimes so slight 

 as only to be detected by careful examination and comparison of 

 the two pasterns. In such cases, of course, the limbs must be placed 

 as nearly as possible in similar positions. Exostoses on the lateral 

 surfaces of the bones are best seen from the front ; those on the 

 anterior surface from the side, and from the height of the affected 

 foot. Diagnosis is also assisted by palpation and comparison of 

 the two joints. 



