THE EFFECT OF POSITION. 251 



the muscles and tendons, and rupture of the fibres, 

 through catching the hind leg on timber when going at 

 full speed. 



The hocks will give more trouble than all the rest of 

 the parts prone to disease in the animal horse, and 

 greater difficulty will be experienced in deciding on the 

 existence of a spavin unless the exostosis be consider- 

 able, than a person not conversant with the different 

 formation of the bones of the hocks would be able to 

 credit. So much depends upon the position of the leg 

 at the time of examination, and on the difficulty there 

 is in making a horse adopt the position required. In 

 addition to which, many horses have largely developed 

 protuberant heads of the internal bones of the hock, 

 which are very frequently mistaken for exostosis ; 

 though it is a perfectly natural though larger formation 

 than that ordinarly met with. 



When exostosis, or a real spavin, exists, it may be 

 discovered without any difficulty by standing behind 

 the horse's hocks, and passing the hand down the lateral 

 edges of the internal bones, which will feel abrupt, 

 irregular, and rarely ever of the same size on both 

 hocks. The sheaths of the tendons of the hind legs 

 must then be cautiously examined, more especially as 

 they approach the fetlock joint, for they very fre- 

 quently become ruptured in hilly countries. 



The horse must now be walked quietly in a direct 

 line from the person conducting the examination, and 

 trotted quietly back again. 



About fifty yards is the most convenient distance for 



