MECHANISM OF THE FETLOCK JOINT, 



57 



vary according to the slope of the pastern and hoof, and according to the 

 length from the fetlock to the toe. Hence (pp. 42 to 44), the shorter 

 is the distance of the toe from the direction of the cannon-bone, or from 

 that of the back tendons, the greater will be the mechanical advantage at 

 which the back tendons will act; and vice versL On the other hand, we 

 may see that the more is the mechanical gain, the worse will the fetlock 

 act as a spring, which function is all-important in saving the limb (especially 

 the fore one) from the injurious effects of concussion. It is evident that 

 the distance of the weight (or power) from the fulcrum (F) is influenced 

 by the length and slope of the pastern; it being greatest when the pastern 

 is long and oblique, and least when that part is short and upright. I may 

 point out that increased growth of hoof, either at the toe or heel, will 



Fig. 39.— 1ST Order. 



Fig. 40.— 2ND Order. Fig. 41.— 3RD Order. 

 Levers of the Hock. 



affect the slope in question, and that the thickness of horn at the toe will, 

 of course, influence the length from the fetlock to the toe. As a practical 

 point I may remark that the toe (except in the treatment of some forms 

 of disease) should always be kept low, and that shoes should be no 

 thicker at the toes than what would be sufficient to enable them to stand 

 " wear." I have alluded to this subject furtlier in my Veterinary Notes for 

 Horse Owners. 



