2. It arises also as a result of all those alterations in the direction of the limbs which tend to remove the quarters from contact with the ground (contraction of the flexor tendons, spavin,—Fig. 202). 3. It may arise gradually from neglect of the hoofs of horses running barefoot. 4. It may arise from excessive shortening of the toe in relation to the quarters. _Shoeing._—The forms of hoofs mentioned in class 1 should be left as they are. The hoofs that fall under class 2 should be dressed and shod until a more natural setting down of the foot is secured. This is brought about by sparing the quarters, and applying a shoe with thickened branches or with heel-calks. Where the service of the animal is exacting and upon hard streets, the toes, especially of the hind shoes, may be made more durable by welding in steel plates. Besides, the shoe should be moderately _base-wide_ around the toe,—that is, should be bevelled downward and outward, should have a _strong toe-clip_, and should be _quite concave at the toe_ and _rolled_. (Figs. 203 and 204). Should the hoof tip forward whenever the weight is thrown upon the limb, a shoe with a spur projecting from the centre of the toe, and turning back and pressing upon the wall just underneath the coronary band, will be of service (Fig. 202). [Illustration: FIG. 203.] [Illustration: FIG. 204. Shoe for stumpy hoofs, viewed from ground-surface, hoof-surface, and in profile.] Only those upright hoofs which are the result of the causes mentioned in 3 and 4 are to be dressed as ordinary hoofs, and if the service required is not too exacting they should be shod with tips (Fig. 201), or with shoes with thinned branches. 3. THE CONTRACTED HOOF. _A hoof which has deviated from its normal form in such a manner that its posterior half, either in part or as a whole, is too narrow, is a contracted hoof._ The walls of the quarters assume an abnormally oblique direction downward and inward towards the median line of the hoof. When contraction affects only one quarter, it is called _unilateral contraction_, or abnormal wryness (Fig. 211). [Illustration: FIG. 205. A fore-hoof with bilateral contraction of the quarters: _a_, spur of horn prolonged from the buttress, which compresses the frog; _b_, narrow median lacuna of the frog.] The buttresses are usually very much prolonged and press upon the frog and cause it to shrink. The bars no longer run in the natural straight direction from the point of the frog backward and outward, but describe a circle passing outward, backward, and inward. [Illustration: FIG. 206. _A_, Defay’s shoe for expanding the quarters of a hoof; _a_, clip apposed to the buttress; _b_, slot sawed at the toe to weaken the shoe; _B_, screw for expanding the Defay’s shoe.]