DISEASES OF BONES 



205 



Except in very unimportant ^particulars tlie bones below the hock 

 resemble those below the knee, and do not, therefore, require special 

 description. 



DISEASES OF BONES 



RING-BONE 



A ring-bone is an enlargement extending over the front, and sometimes 

 also over the back, of the pastern. It consists of a diffused bony excre- 

 scence growing out of or upon the large or small pastern bone, or both. 

 When affecting the former it is described as high ring-bone (fig. 314), 

 when the latter, as low ring-bone (fig. 313). It is common to all classes 

 of horses, but more especially prevalent in cart-horses and thoroughbreds. 



Fig. 313.— Rinti-Bone 



A, Extensor Pedis Tendon. B, Os Siiffraginis or First Phalanx, 

 c, Os Coronie. D, Ring-bone. E, Os Pedis. 



Fig. 314. — "High "Ring- 

 Bone 



Causes. — Horses with upright pasterns, and animals with pasterns of 

 undue length, are specially predisposed to it. The exciting causes are 

 chiefly blows, concussion, and sprains to the joints. Fracture of the 

 pastern is invariably followed by ring-bone in the form of a reparative 

 callus. It is also induced by the too early and severe work imposed 

 on young, undeveloped animals, and especially when attended with bad 

 shoeing, as where the heels are thrown up too high and an upright posi- 

 tion given to the limb. 



Symptoms.- — A hard, unyielding enlargement, more or less promi- 

 nent and extensive, is the characteristic indication of the disease. It passes 

 across the front of one or the other of the pastern bones, and sometimes 



