60 CAUSES OF SPAVIN. 



able become cemented and fixed together, and which is sometimes 

 productive of caries of the articular surfaces of one or more of the 

 joints of the hock. 



The Site of Spavin is the antero- inferior part of the inner 

 side of the hock, immediately beneath the prominence of the joint 

 below. Why spavin should grow upon the inner, and never — or 

 but very rarely indeed — upon the outer side of the hock, there are 

 two satisfactory reasons : — one is, that the inner sides of the limbs 

 are nearer to the central line of gravity than the outer ; the other, 

 that, from the arrangement of the cuneiform bones, the hock joint is 

 so constructed that the inner metatarsal bone is impressed by the 

 superincumbent weight more forcibly, and consequently is com- 

 pelled to yield or descend to a greater degree, than the outer bone. 

 Such a phenomenon as a spavin on the outer side of the hock is all 

 but unheard of : I am not saying it never occurs, nor indeed am I 

 quite sure it would be called a spavin if it did : when any thing of 

 the kind does happen, it is commonly the result of injury. Solley- 

 sell mentions something of the kind, and calls it a jarde ox^jardon. 

 Many years ago, a horse was admitted into the Royal Horse In- 

 firmary, at Woolwich, for a spavin growing directly wpon the 

 front of the hock, opposite to the joint between the lower cuneiform 

 bone and large metatarsal. The tumour was not distinguishable 

 in the ordinary side-view of the hock, nor was there any tume- 

 faction whatever in the usual situation of spavin. Spavins may 

 present themselves simultaneously in hoth hocks : commonly, but 

 one hock is affected, and I do not know that either in this respect 

 manifests any preference over its fellow. Sometimes, after spa- 

 vin has run its course in one hock the other will become affected. 



Causes of Spavin, 



These I shall consider under the heads of predisposing and ex- 

 citing : — 



Predisposition to Spavin may be either constitutional or 

 local: in the former case, lying in breed or constitution ; in the latter 

 in some peculiarity in the formation of the hock, or in the use made 

 of it. Solleysell speaks of spavins being hereditary ; though 

 Gibson's interpretation of this is '* natural weakness." In a paper 



