50 THE A R:\rY HORSE. 



assists in the circulation of the blood through the veins of the 

 foot. When weight is placed upon the foot the pressure on 

 the plantar cushion forces the blood upward through the veins ; 

 then, wdien the foot is lifted and the pressure is removed from 

 the horny frog and plantar cushion, the veins of the frog again 

 fill with blood, and this pumping action is repeated with each 

 step. Proof of this statement is seen when a digital vein is cut, 

 by accident or in experiment. If the horse is walked, a jet 

 of blood spurts out each time he puts the foot to the ground; 

 but if he is allowed to stand the blood flows in a stead}" stream 

 from the vein. Great injury to the foot results from starting 

 the horse off suddenh^ at a fast gait on a hard road after he 

 has been standing for some time or when he first comes out of 

 the stable. The circulation (just explained) and the structures 

 of the foot should have time to gradually adapt themselves to 

 the change from rest to severe work. 



Moisture. 



The wall of the healthy hoof, is, b}^ weight, about one-fourth 

 water, the sole more than one-third, and the frog almost one- 

 half. This water is supplied by the blood and preserves the 

 horn in a tough and elastic condition. The periople, which 

 covers the wall, prevents the evaporation of water, and there- 

 fore should ncrer be rasped. As there is no similar covering 

 for the sole and the frog, the layers of horn on their exposed 

 surfaces dry out and die. The dead layers are hard and brittle, 

 and gradually fall or flake off; but. as the}^ preserve the mois- 

 ture in the layers of live horn beneath, they should not be 

 removed in preparing the hoof for shoeing. 



Shoeing. 



Shoeing is a necessary evil, but by remembering the func- 

 tions of the various parts of the foot the damage resulting may 

 be limited to a comparatively small ariiount. 



The following rules may serve as a guide for the shoeing of 

 healthy feet: 



1. The wall being the weight bearer should be pared per- 

 fectly level or the foot will be thrown out of its true position, 

 causing extra strain on some of the ligaments. 



2. Fit the shoe accurately to the outline of the foot; do not 

 alter the latter to fit the shoe. Easping away the exterior of 



