144 THE SURGICAL ANATOxMY OF THE HORSE 



chronic form is, however, as we have already stated, much more fre- 

 quently of a dropsical nature, and such enlargements are usually found 

 in heavy horses with upright hocks in which the tuber calcis is short 

 and ill-developed. In such hocks the gastrocnemius and flexor per- 

 foratus are not so effective in extending the hock, since the leverage with 

 which they are provided is not so great as in animals in which the tuber 

 calcis is large and well developed. Consequently much more work in 

 extending this joint has to be undertaken by the flexor perforans. Since 

 conformation is transmitted from sire and dam, a predisposition to the 

 enlargement of this sheath may thus be inherited. These chronic 

 swellings, although most unsightly, are not very serious, for they may 

 attain large proportions without in any way interfering with the action 

 of the joint. Should there be any interference at all, it is purely 

 mechanical. Animals affected with thoroughpin frequently work hard 

 throughout life without suffering any inconvenience whatsoever. 



Various methods of treatment are in use. A reduction in the size of 

 the thoroughpin may frequently be made by applying trusses or pressure 

 bandages. Some rely on the application of a blister, whilst others claim 

 good results for line-firing. The contents of the sheath may be 

 evacuated ; and there is obviously much less danger in opening this sheath 

 surgically than in performing the same operation in the treatment of 

 bog spavin. Dean's aspirator should be used, and the membrane syringed 

 out with a solution of iodine, the operation being exactly similar to that 

 performed in the treatment of bursal enlargements elsewhere, which has 

 already been described. 



THE POINT OF THE HOCK— CAPPED HOCK 



It has already been remarked in our superficial examination that the 

 projection known as the point of the hock is caused chiefly by the 

 underlying summit of the tuber calcis. The particular portion of the 



