422 DISEASES OF THE HORSE. 
of necessary moisture; this, in turn, reduces the elastic properties of 
the horn and diminishes the transverse diameter of the heels; weak 
feet, or those in which the horn of the wall is too thin to resist the 
tendency to spread, whereby the soft tissues are easily lacerated. 
Wide feet with low heels are always accompanied with a flat sole 
whose posterior wings either rest upon the ground or the shoe, and 
as a consequence are easily bruised; at the same time the arch of the 
sole is so broad and flat that it can not support the weight of the 
body, and in the displacement which happens when the foot is rested 
upon the ground the soft tissues are liable to become bruised or torn. 
It is universally conceded that shoeing, either as a direct or predis- 
posing cause, is most prolific in producing corns. One of the most 
serious as well as the most common of the errors in shoeing is to be 
found in the preparation of the foot. Instead of seeking to maintain 
the integrity of the arch, the first thing done is to weaken it by freely 
paring away the sole; nor does the mutilation end here, for the frog, 
which is nature’s main support to the branches of the sole and the 
heels, is also largely cut away. This not only permits of an excessive 
downward movement of the contents of the horny box, but it at the 
same time removes the one great means by which concussion of the 
foot is destroyed. As adjuncts to the foregoing errors must be added 
the faults of construction in the shoe and in the way it is adjusted 
to the foot. An excess of concavity in the shoe, extending it too far 
back on the heels, high calks, thin heels which permit the shoe to 
spring, short heels with a calk set under the foot, and a shoe too 
light for the animal wearing it or for the work required of him, are 
all to be avoided as causes of corns. A shoe so set so as to press upon 
the sole or one that has been on so long that the hoof has overgrown 
it until the heels rest upon the sole and bars becomes a direct cause 
of corns. Indirectly the shoe becomes the cause of corns when small 
stones, hard, dry earth, or other objects collect between the sole and 
shoe. Lastly, a rapid gait and excessive knee action, especially on 
hard roads, predispose to this disease of the feet. 
Symptoms.—Ordinarily a corn induces sufficient pain to cause 
lameness. It may be intense, as seen in suppurative corn, or it may 
be but a slight soreness, such as that which accompanies dry corn. 
It is by no means unusual in chronic corns to see old horses appar- 
ently so accustomed to the slight pain which they suffer as not to 
limp at all. But they are generally very restless. They paw their 
bedding behind them at night and often refuse to lie down for a long 
rest. The lameness of this disease, however, can hardly be said to be 
characteristic, for the reason that it varies so greatly in intensity ; but 
the position of the leg while the patient is at rest is generally the same 
in all cases. The foot is so advanced that it is relieved of all weight. 
and the fetlock is flexed until all pressure by the contents of the hoof 
