Green horses with wide hoofs, just from the pasture, are particularly liable to this form of contraction. As a rule, the lameness does not disappear completely until the wall has assumed its natural, straight direction by growing down properly from the coronary band. In dressing the hoof and applying the _bar-shoe_, care must be taken that the lower border of the wall underneath the painful area is lowered so much that it will not receive direct pressure from the shoe. (_b_) _Contraction of the Sole._—This is accompanied by an unnatural direction of the wall. Instead of the wall being straight from the coronet to the shoe, it describes a curve whose convexity is outward (keg-shaped, claw-shaped when seen from the side) (Fig. 210). The hoof seems constricted (tied in) at the coronet and at its plantar border, the sole is abnormally concave (arched), and the plantar surface of the hoof is considerably shortened from toe to heel. It happens in both shod and unshod horses, with otherwise strong hoofs, but is quite rare. It is occasionally associated with navicular bursitis (“navicular disease”). _Causes._—Principally dryness, too little exercise, and shoes without horizontal bearing-surface. [Illustration: FIG. 210. A fore-hoof with a contracted sole, properly shod: _a_, toe convex in profile; _b_, shoe fitted full all around, and “bearing-surface” inclining outward; _c_, outer border bevelled base-wide.] The treatment is correspondingly simple: The shoes should be flat, fitted full all around to coax the wall out at every point, and the outer border bevelled base-wide, so as to furnish a base of support that is wider and longer than the hoof. In moderate contraction of the sole, the bearing-surface of the shoe should be perfectly horizontal, but if the contraction be very pronounced, the entire bearing-surface should incline downward and outward (even at the toe). No toe-or side-clip should be used. The shoe should be reset every two weeks; the sole kept so thin by paring that it will spring under thumb pressure, and kept moist by washing, tubbing or “stopping,” and the animal given moderate exercise daily. _In all forms of contraction of the hoof abundant exercise and the maintenance of the natural pliancy of the horn by daily moistening (washing) with water are absolutely necessary for successful treatment._ 4. THE WRY HOOF. If one side wall and quarter is steep, and the other very slanting or oblique, we term such a hoof a “wry hoof.” Such a hoof divided in the middle line presents two very _dissimilar_ halves. There are three classes of wry hoofs: 1, normal wry hoofs (see Figs. 63-66); 2, pathological wry hoofs, or hoofs contracted in one quarter (see contracted hoofs); 3, wry hoofs which are the result of improper shortening of the wall and of neglect in horses running barefoot.