so THE CANADIAN HOESE 



to enlargement of the bursa of the perforans tendon. 

 The term blood-spavin is given to it when the vein is made 

 to stand prominently out from the bulging of the capsule. 

 This term is unnecessary and unscientific, unless we have a 

 varicosity of the vein, which is very rare, indeed, at this 

 joint. 



Causes. — Like the preceding, disease, and, indeed, all 

 diseases of joints, over-exertion is the great cause. In 

 young, growing animals, it frequently appears without any 

 assignable cause, more especially in rough, coarse-boned 

 animals ; but in them it generally disappears as they grow 

 up. In older animals, however, the case is more serious. 

 From the increased friction during hard work, we have an 

 increased secretion of synovia, which distends the capsule ; in 

 some cases the cartilages covering the bones are abraded, 

 and in some bad cases the friction goes on till the cancel- 

 lated structures of the bone are exposed. It is in this case 

 that the condition called porcelaneous deposit is seen. Such 

 severe cases are generally accompanied by osseous deposits 

 around the joint. 



Symptoms. — It is easily recognised. Instead of the hock 

 presenting its natural smooth outline, you find a bulging in 

 front, which, on examination, is found to be soft, pufiy, and 

 apparently filled with fluid. In thorough-pin you have a 

 similar enlargement on each side, fiUing up the hollow be- 

 tween the point of the hock and the joint, which can be 

 pushed from side to side, and which, when pressed equally 

 on both sides, enlarges in front, and vice versa. Lameness 

 is not often a symptom, unless abrasion is going on, or 

 ossific deposits accompany it. 



Treatment. — In many cases in young, growing animals 

 treatment is not required. As the animal grows, nature re- 

 moves the superfluous fluid, and leaves the hock as fine as 



