In this case, when the entire weight is thrown on to the heels, the portion of wall posterior to the crack is bound to participate unduly in the downward movement, and so tend to widening of the crack at its highest point.

[Illustration:  FIG. 93.—­THE BEARING ‘EASED’ BY ‘SPRINGING’ THE HEEL OF THE SHOE.]

We have already referred to the matter of ‘clips.’  In no case, whether the crack be at the toe or in the quarters, should a clip be placed immediately below it.  If the crack is at the toe, the usual clip should be dispensed with, and a clip at each side made to take its place.  At the same time care should be taken to avoid throwing the weight far forward.  For that reason a shoe with calkins or with very high heels should be removed, and a shoe with an ordinary flat web substituted.

In the case of quarter-crack, where the constant movement of the parts under expansion and contraction of the foot makes itself most felt, it is wise to apply a shoe with clips fitting moderately tight against the inside of the bars.  By this means movement will to a very large extent be curtailed.

Where a marked tendency to contraction is found, as is often the case with quarter-crack, then the shoe with the clips may be rendered more marked in its operation by giving to the outer face of each clip—­that face applied to the bar—­a slope from above downwards and outwards.  In other words, a slipper shoe should be applied and the contraction given equally as much attention as the sand-crack itself.

Where the crack is situated far back in the quarter, and easing of the bearing cannot be accomplished without tending to spring the heels, then the most suitable shoe is a bar shoe.  With it the bearing may, of course, be eased in exactly the position required, and the heels still allowed to take their fair share in bearing the body-weight, and thus assist in closing the crack.  The bar shoe, if properly fitted, gives us also a bearing on the frog, and aids greatly in counteracting contraction.

2. Curative.

(a) The Application of Dressings to the Lesion.—­In the case of a recent crack, deep, and attended with haemorrhage, the foot should be thoroughly cleansed.  Where possible, a constant flow of cold water from a hose-pipe should be allowed to run over the foot.  By this means the inflammatory symptoms will be held in check and pain prevented.  Later the shoe may be eased at the required place, and a blister applied to the coronet.  This, with rest, will sometimes prove all that is needed.

Should a crack be of old standing, and complicated by the presence of pus, a course of hot poulticing will often prove of benefit.  The poultice should be medicated with any reliable disinfectant, and should be renewed, or at any rate reheated, two or three times daily.  The crack itself should be thoroughly cleaned after the removal of each poultice, and a concentrated antiseptic solution—­such as Tuson’s spts. hydrarg. perchlor., carbolic acid, and water, (1 in 10) or liquor zinci chlor.—­poured into it.  On discontinuing the poulticing, the strength of the antiseptic solutions may be decreased, the parts rested by correct shoeing, and a blister applied to the coronet as before.