extreme upper limit of the crack; (4) by
drawing two horizontal grooves, one at its upper and one at its lower end
(see Fig. 96).

[Illustration: FIG. 94, FIG. 95, FIG. 96. In Figs. 94, 95, and 96 the thick
black lines illustrate the positions of the various grooves made with the
firing-iron for the purpose of immobilizing a quarter sand-crack.]

The points to be observed in carrying out this line of treatment are simple
enough. In all cases see that the crack is rendered as clean as possible
by the use of suitable dressings, and if an excess of horn is present
immediately around it, as in the case of a long-standing and complicated
lesion, have it thinned down by rasping.

All that is then needed is one or two moderately sharp, flat firing-irons.
The groove is then burned into the horn in the positions indicated, and
that portion of the wall containing the sand-crack thus prevented from
participating in the movements of the foot. For our own part, we consider
the V-shaped incision, or either of the horizontal methods of grooving,
preferable to lines running in the direction of the horn fibres. With the
latter there is certainly a greater tendency to the formation of new cracks
than with either of those we advocate. The V-shaped incision we consider
most suitable of all, for the reason that by its means a greater degree of
immobility is conferred upon the necessary portion of the wall.

Whichever method is adopted, care should be taken to carry the grooves deep
enough into the horn, taking them down as near as possible to the sensitive
structures. At the same time, especial care should be exercised in not
carrying them too deep at their extreme upper limit, or in that case the
liability to the formation of fresh cracks in those positions will be
greatly increased.

After grooving, a sharp blister should be applied to the coronet every
three or four weeks, and the animal, if free from lameness, put to work.

_(c) By stripping away a V-shaped Portion of the Wall around the
Crack_.--This method is only indicated when the crack is greatly
complicated by the presence of pus, or by the growth of adventitious horn
on the inner surface of the wall. A radical cure is thus obtained, but the
animal for a longer time incapacitated from work.

The operation is best performed by first grooving a line to connect the
points _a_ and _c_ (Fig. 97). This should run immediately under the
coronary margin of the wall, and should stop