Should pain unfortunately continue, the discharge remain, and a state of fever reveal itself, then it may be understood that the suppurative process has not been checked, that a portion of necrosed ligament, cartilage, or bone still remains, which, surrounded as it is by pus organisms and putrefactive germs, is sufficient to excite a constant irritation and maintain the internal structures in a state of infection.  In other words, we have what is known as a quittor.

This will call for deeper operation.  The horn of the wall must be removed, and the diseased structures, whether gangrenous keratogenous membrane, necrosed ligament, or carious bone, carefully excised or curetted.  This will be better understood by a reference to the chapter on Quittor, where the means for carrying out the necessary operative measures will be found described in detail.

Surgical Shoeing for Corn.—­In the case of an ordinary dry corn, where the injury has been definitely ascertained to be accidental, no alteration in the shoeing will be necessary.  Where, however, the corn is attended with a more than ordinary degree of inflammation, or where for some reason or other excessive paring has been practised, then it will become needful to shoe with a special shoe.  The object to be attained is the removal of pressure from that portion of the wall next to the seat of corn.

The most simple shoe for effecting this is the ordinary three-quarter shoe.  The only way in which this differs from the ordinary shoe is that about an inch and a half of that branch of the shoe adjoining the corn is cut off (Fig. 102).  If at the same time contraction of the heels exists, then, perhaps, a better shoe is that known as the three-quarter bar (Fig. 103).

Or, if preferred, a complete bar shoe such as that described for sand-crack may be used, and the upper portion of the web in contact with the foot at the seat of corn thinned out so as to avoid pressure on the wall at this point.  With this shoe we shall at the same time supply a certain amount of pressure to the frog, and aid in the healthy development of the part indirectly involved in the disease.

The same pressure may also be given to the frog, and protection afforded the sole, by the use of a leather sole, or rubber pad on leather, as described when dealing with contracted feet.

A further method of relieving pressure on this portion of the wall, without removing the wall itself (a practice which should never be advised) is to make certain alterations in the web of the shoe.  This may be done in one of two ways.

[Illustration:  FIG. 102.—­THREE-QUARTER SHOE.]

[Illustration:  FIG. 103.—­THREE-QUARTER BAR SHOE.]

In the first, that portion of the bearing surface of the heel of the shoe is ‘dropped’ about 1/8 inch from the plane of the remainder, so that the shoe at this position does not come into contact with the foot at all (see Fig. 104).