A SPRAIN OR STRAIN. 



213 



ments and concussion. High-calked slioes often cause it. The 

 hock tied in below, or sickle-shaped, is the form most suscepti- 

 ble to spavin. The lameness of bone spavin is, as a rule, remov- 

 able in the young and middle aged, but generally incurable in 

 horses past twelve years or their prime. 



Pathology. — Bone spavin is an inflammation of the bones 

 and inter-osseous ligaments. The inflammation originates in the 



Fig. 55— A. Perfect Hock. 



cancellated structure of the interior of the bones; an exudation 

 is gradually thrown out between the bones and their cartilage, 

 perverting the nutrition of the latter, whereby it ulcerates and 

 is removed, leaving the exposed surfaces of bone in contact with 

 each other and their cancellated structures in apposition, thus 

 enabling their vessels to communicate with each other. Along 

 with the destructive process going on in the interior of the bones, 

 an exudate is found upon their periosteal surface, extending from 



