RING-BONE. 



877 



at the points of insertion of the lateral ligaments, and produces 

 swellings on the inner or outer side of the joint. Post-mortem 

 examination shows the articular surface to be healthy, but the liga- 

 mentous apparatus is thickened, and more or less well-developed 

 exostoses exist at the points of insertion of the lateral ligaments, 

 though they also occur at the spot where the posterior ligaments 

 of the coronet-joint become attached to the suffraginis. As the 

 articular cartilage is free from disease, this condition has by some 

 been named false ring-bone. 



(3) Rachitic ring-bone. In young animals suffering from rachitis, 



Fig. 496. — Articular ring-bone. 



Fig. 497. — Periarticular ring-bone. 



thickenings sometimes persist on the lower extremity of the suffraginis 

 and at the upper extremity of the coronet bones, and, as they cause 

 swelling around the joint, have been described as ring-bones. In 

 such cases, however, there is no pathological change either in the 

 joint proper or in its ligaments. 



(4) The term " traumatic ring-bone " includes all enlargements 

 about the coronary joint produced by periostitis due to other (usually 

 traumatic) causes, whether following treads on the coronet or acute 

 inflammatory disease of neighbouring parts, wounds, &c. This 

 classification meets practical requirements, for, in clinical diagnosis, 

 it is quite possible to distinguish the different forms, and to modify 

 the prognosis according to circumstances. 



Causes. The cause of the coronet-joint being so frequently the 



