44 MANUAL FOR ARMY HORSESHOERS. 



work above. This compression causes the digital cushion and frog 

 to spread out to the sides, pressing outward energetically the carti- 

 lages, the bars, and the walls at the heels and quarters. Tliis is 

 called expansion. It does not occur in a foot so shod that the frog 

 can not come in contact with the ground. 



When the weight is removed from the foot the digital cushion and 

 frog return to their normal shape, allowing the cartilages and the 

 quarters to return to their original positions. This is called contrac- 

 tion. Upon the alternate displacing and returning of these parts of 

 the foot, nature relies for necessary beneficial effects. 



This expansion and contraction diminish the jar to the foot and 

 leg. The action is increased as the horse increases his gait. This 

 action also assists in the circulation of the blood through the foot. 

 When expansion occurs the blood is forced out of the veins in the 

 digital cushion up into the pastern region, where the valves prevent 

 its return to the foot. When contraction occurs and the parts 

 resume their normal positions fresh blood is drawn from the arteries 

 for the nourishment of the tissues of the foot. For this reason the 

 horse should have daily exercise to gi^^e the tissues of the foot their 

 proper noiuishment. When the horse is taken out to work he should 

 be walked at first to allow the circulation to adjust itself to the 

 change from rest to work. 



