Contraction affects front feet, especially those of the _acute-angled_ form, more often than hind feet. In order to determine whether or not a hoof is too narrow, we should always examine the frog and its lateral lacunæ. If the frog is small and narrow, and the lateral lacunæ very narrow and deep, there can be no doubt but that the hoof is too narrow (contracted). _The causes_, aside from too little exercise, are chiefly errors in shoeing, such as weakening the posterior half of the hoof, leaving too long a toe, either neglecting to remove the spurs of horn which grow from the buttresses and press upon the frog, or removing them incompletely, and using shoes whose branches are either _too wide apart_ or are inclined downward and inward, so that under the weight of the body _the heels are squeezed together_ and contraction is favored. _Prevention and Treatment._—First, it should be borne in mind _that whatever exercises moderate pressure upon the sole, frog, and bars tends to expand the hoof_. The action and value of the various shoes, frog-, and sole-pads, are measured by this rule. For this reason a shoe with heel-calks is never advisable if an open flat shoe without other means of relief can be used. Furthermore, since contraction is the parent of nearly all diseases of the hoof (corns, quarter-cracks, bar-cracks, thrush of the frog), we should use the greatest care to =prevent= it by dressing the hoof as described on pages 98 to 103, using flat shoes with a =horizontal bearing-surface for the quarters=, giving =abundant exercise, preventing drying out of the horn=, and allowing the animal to go barefoot whenever possible. _Where the contraction is but slight_ the foregoing rules will be found sufficient. _In very pronounced contraction, where the hoof is not acute-angled, an expansive shoe_ with clips raised at the ends of the branches to press against the buttresses may prove very advantageous; but under no conditions should violence be used in expanding the heels with the expanding-screw. This is an act of extreme delicacy, and should be performed only by experienced veterinarians.