_In very pronounced contraction of one or both quarters of hoofs of every degree of obliquity_ we may obtain a continuous expansive action by the use of one of the numerous V-shaped springs, of which the _Chadwick spring_ is the best (Fig. 207 and 208). After levelling the wall and thinning the branches of the sole, the points of the spring are set against the =buttresses=, the apex of the spring moved to and fro till the points have bored well into the horn, when the apex is laid against the sole at the toe, the sole filled with tar and oakum and covered by a leather sole, and a bar-shoe applied. If the contraction be less pronounced, or if the frog be much shrunken we may place a Chadwick spring beneath a rubber bar-pad with a short shoe. The spring may be stiffened from shoeing to shoeing, first by introducing the ferrule at the apex of the spring and later by shifting the ferrule toward the shoulder (Figs. 207, _b_, and 208, _b_). [Illustration: FIG. 207. The Chadwick spring for expanding contracted quarters: _a_, apex of spring; _b_, ferrule to stiffen the spring; _c_, point which is buried in a buttress of the hoof.] [Illustration: FIG. 208. A fore-hoof showing a Chadwick spring in proper position: _a_, Chadwick spring; _b_, ferrule to stiffen spring as desired; _c_, uncompressed spring before it has been engaged against the buttresses; _d_, buttresses in which points of spring are buried.] For contracted hoofs of the _acute-angled form_ we use the bar-shoe, and if there are other diseases of the hoof present, or if we wish a more rapid and continuous expansive action, we use also a leather sole with foot-packing with or without a buttress spring. A foul frog should be properly cleansed, and then disinfected with pine-tar thinned with alcohol or crude wood-vinegar (pyroligneous acid). Further curative measures are: turning the horse out without shoes (expensive and seldom practicable); applying tips; using shoes the bearing-surface of whose branches inclines downward and outward (unilateral contraction requires but one branch to be so constructed); hoof-pads of rubber (Figs. 145, 146, and 147), straw, rope, cork, hoof cement, etc. Special forms of contraction are distinguished, and are as follows: (_a_) _The Contraction of Wide Hoofs._—This contraction is manifest as a concavity or groove in the wall just below the coronet, usually at the quarters, though sometimes extending entirely around the foot parallel to the coronary band (Fig. 209). Pain is produced in the contracted area by lightly tapping the horn, but not by moderate pressure with the hoof-testers. [Illustration: FIG. 209. Wide fore-hoof with “coronary contraction”: (_a_) broad shallow groove in each quarter, and disappearing toward the toe.]