396 DISEASES OF THE HOESE. 



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 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 become 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 lame- 

 ness. 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 to see old horses having chronic corns apparently so 

 accustomed to the slight pain which they suffer as not to limp at all ; 

 but these animals are generally very restless ; they paw their bedding 

 behind them at night, and often refuse to lie down for any lengthened 

 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 

 is removed from the heels. In suppurative corn the lameness subsides 

 or entirely disappears as soon as the abscess opens. When the injured 

 tissues are much inflamed, as may happen in severe and recent cases, 

 the heel of the affected side, or even the whole foot, is hot and tender 

 to pressure. In dry corn, and in most chronic cases, all evidences of 

 local fever are often wanting. It is in these cases that the patient 

 goes well when newly shod, for the smith cuts away the sole over the 

 seat of injury until all pressure by the shoe is removed, and lowers 

 the heels so that concussion is reduced to a minimum. 



If a corn is suspected the foot should be examined for increased 

 sensibility of the inside heel. Tapping the heel of the shoe with a 

 hammer and grasping the wall and bar between the jaws of pincers, 

 Avith moderate pressure, will cause more or less flinching, if the dis- 

 ease is present. For further evidence the shoe is removed and the 

 heel cut away with the drawing knife. As the horn is pared out, not 

 only the sole in the angle is found discolored, but in many instances 

 the insensible laminae of the bar and wall adjacent are also stained 



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