In any case, having once determined the position of the lines, they should be plainly marked out with chalk, and then viewed from a distance with the foot on the ground, in order to judge of their regularity.  If we are satisfied with them, we then lightly mark them with the saw, with the hot iron, or with the knife, whichever instrument we may be intending to use.

Unless the details are methodically carried out as here described, it is probable that more of the foot will be isolated than is necessary, and that as a consequence very little is left to which to nail the shoe.

[Illustration:  FIG. 149.—­DIAGRAM ILLUSTRATING THE POSITION OF THE GROOVES MADE IN THE HOOF IN COLONEL SMITH’S OPERATION FOR SIDE-BONES. 1, 2, and 3, show the grooves in the wall in the order in which they are made; 4 shows the groove made at the junction of the sole with the wall.]

The incisions are then made with the saw or the knife, with the foot held in a convenient position by an assistant.  That usually found most comfortable for the first incision is with the foot held forwards and placed on an assistant’s thigh in the position adopted for ‘clenching up’ when shoeing, while that for the rear incision is with the animal’s knee flexed, and the foot held well up to the elbow.  In this, however, each operator will suit himself.

Should the preliminary steps in making the incisions be performed with the iron, it will be easiest done with the foot on the ground.

When the incisions through the wall are complete, our attention must be given to the sole.  A drawing-knife is here used, and a further incision made over the white line so as to destroy the union of the sole with the wall between incisions 1 and 2, and so completely isolate the portions of wall included within the four grooves (see groove 4, Fig. 149).  When this is done it should be found that the portions of the isolated wall spring readily to pressure of the thumb.

The inferior or wearing margin of the isolated wall must now be so trimmed that it takes no bearing on the ground when the opposite limb is held up by an assistant and full weight placed upon the foot.

For a day or two after the operation lameness is intense.  This is to be treated with hot poultices or hot baths, and and soon disappears.  Three to four days later a bar shoe is nailed on (taking care that the bearing of the quarters is still eased), and the hot poultices still continued.  Four days later still walking exercise may be commenced, to be followed shortly afterwards by trotting.  At about the twelfth day some animals may conveniently be put to work, while in other cases a fortnight, or even a month, must elapse before this can be done.  When put to work early, it is wise to fill in the fissures made in the wall with hard soap, with wax, or with a suitable hoof dressing, in order that irritation of the sensitive structures with outside matter may be prevented.