610 OPERATIONS ON THE FOOT. 



wide shoe, too thin, may also contribute to the genesis of corns, 

 because, then, the shoe helping, with the intensity of the reactions 

 on the pavement or on too hard and stony roads, the shoe soon 

 gives under the foot, and compresses the sole and tissues beneath. 



The manner in which the shoe is put on may also be a cause 

 of corns ; the shoe ought to rest exclusively on the inferior border 

 of the wall, and not touch the sole ; when it is too narrow it may 

 be a cause of contusion or of contraction ; if too wide it prevents 

 the natural expansion. It is upon horses long shod that the wrong 

 application of the shoe as a cause of corns is observed. As a con- 

 sequence of the growth of the hoof, the shoe no longer sufficiently 

 protects the plantar border of the foot, the heels of the shoe being 

 inward and pressing on the branches of the sole ; this is especially 

 the case when the shoe is thinned by wearing ; it yields, and easily 

 bruises th^ parts of the sole on which it rests ; high caulks, on a 

 branch abeady too short, or too thin, act the more injuriously be- 

 cause, not being concentrated on the projection of the caulk, the 

 branch gives away sooner, and presses still more on the heels. 



The shoe becomes an indirect cause of corns, when hard sub- 

 stances, as stones or dry earth, are found between its superior and 

 inferior face on the sole, or between the frog and the internal bor- 

 der of the branches of the shoe ; this is a secondary cause, which 

 was formerly considered of great importance. 



The work of horses has a great influence, corns being very fre- 

 quent in horses which work on pavements and stony and hard 

 roads. They are rare in country horses, but common in those of 

 great cities ; a rapid gait contributes to their development on 

 account of the great pressure on the ground. The seasons have 

 also an influence, dry and warm weather depriving the hoof of its 

 moistiure, and by preventing its elasticity of motion, increasing the 

 effect of pressure upon the tissues. 



Emigration has been considered a cause of corns. Horses 

 coming from the north of Germany are mentioned as having been 

 rapidly affected by them after being in large cities. But if the 

 change too suddenly made from soft to dry bedding is an effective 

 cause, the mode of shoeing can also be considered as a stimulating 

 cause. The same is true with respect to the African horses, which 

 are generally free from the disease in their native country, but 

 frequently suffer with them when brought to Prance, and submitted 

 to a mode of shoeing so different from that of the Arabs. 



