CORNS. 
701 
apait, the inner heel is most generally affected ; in the opposite confor¬ 
mation, the outer. The weaker the horn of the heels, the more readily 
do such injuries occur : rings on the surface of the heels suggest the 
existence of corns. Abnormally narrow feet are generally the seat of corns, 
and in contracted heels they are almost always present. But wide hoofs 
are also liable to them ; in such case the corn being an injury of the sole, 
whilst in narrow hoofs the wall is more often affected. 
The principal external causes are faulty shoeing, especially improper 
paring, the use of too short or too narrow shoes, or allowing the shoes to 
remain on for too long a time. As corns are very rare in unshod feet, the 
idea obtained currency that they were always produced by the pressure 
of the shoe. 1 or this reason farriers often endeavour to prevent the 
Fig. 297.—Three-quarter bar shoe, a, Seat 
of the corn. 
Fig. 298.—Ordinary three-quarter 
shoe. 
injury by rasping away the inner wall, so that it no longer touches the 
shoe. The result shows, however, that this idea is erroneous, for corns 
occur just the same, and, in addition, a sand-crack often forms at the 
coronet. It therefore seems clear that the heel should be supported by 
the shoe ; if not, it descends, and leads to rupture of the sensitive laminae. 
The attempt to remedy the evil thus leads to its propagation. 
Prognosis. Although corns are so common that their absence in 
animals working in large towns is almost an exception, yet they give rise 
to much trouble. Severe consequences, however, only follow when the 
point of origin becomes infected; and as infection almost always takes 
place from without, it is of the greatest importance to protect the 
haemorrhagic spot against the entrance of foreign material. Sometimes, 
however, the horn is so defective that no precautions seem sufficient to 
prevent it, and then the animals suffer habitually, and little hope of cure 
