The following local symptoms may occur: The wall of the foot at the quarters may appear drawn in at its superior or inferior portion. Sometimes one or both quarters are perpendicular, or nearly so. The foot then appears too narrow at the heel, too elongated and less rounded than normal. The changes in the appearance of the inferior surface of the hoof vary. The changes here may be so slight that they are not noticed. In well advanced and neglected cases the arch of the sole is increased, the frog is narrow and atrophied and the bars high and perpendicular. Corns may accompany the contraction. The foot may feel feverish. The animal may manifest the pain in the feet when standing at rest by pointing and changing their position. When lameness is present, it may resemble that occurring in inflammation of lateral cartilages and navicular disease.
Preventive treatment is of the greatest importance. This consists in giving the feet an opportunity to take up moisture when they are exposed to abnormal conditions and become feverish. Under such conditions, it is advisable to occasionally remove the shoes and turn the animal into a pasture or lot. It is best to do this in the fall or winter when the ground is wet. If this can not be practised, the shoes should be removed and a poultice of ground flaxseed and bran, equal parts, applied to the feet for a period of eight or ten hours, daily for a week or two. A plank trough six inches deep, two feet wide and as long as the stall is wide may be filled with a stiff clay, and the horse made to stand with its front feet in the clay bath for ten or twelve hours daily. When grooming the horse, the foot should be cleaned with a foot-hook and washed with clean water. Hoof ointments should be avoided so far as possible. The importance of fitting the shoe to the foot, avoiding the too free use of the rasp and hoof knife and resetting or changing the shoe when necessary can not be overestimated. Shoeing the animal with a special shoe is sometimes necessary. It is not advisable to attempt the forcible expansion of the quarters. Lowering the heels by careful trimming of the wall and sole and permitting frog pressure may be all the special attention required.
SAND-CRACK.—A fissure in the wall of the foot running in the same direction as the horny fibres, or a seam in the wall resulting from the healing of the fissure is termed sand-crack. The position and extent of the fissure or seam vary. It may involve the wall of the toe (toe-crack) (Fig. 41) or quarter (quarter-crack) (Fig. 42). It is superficial or deep, according to the thickness of the wall involved; complete or incomplete, depending on whether it extends from the bearing margin of the wall to the coronary band or only a portion of the distance; simple, when the horny tissue only is involved; and complicated, when the sensitive tissue beneath becomes injured and inflamed. Cracks of long standing usually have thick, rough margins.
The causes of this unsoundness are poor quality of horn, improper care and injuries. Sand-cracks commonly occur in hoofs that are dry and brittle and have thin walls. In young horses incomplete cracks due to the wall becoming long and breaking off in large pieces are common. Unequal distribution of weight, the result of unskilled shoeing, or any other condition that may cause the foot to become unbalanced, using the foot rasp too freely, and such diseases as quittor, corns and contracted quarters subject the animal to this form of unsoundness. Any injury to the coronary cushion that secretes the fibres of the horny wall may result in either toe- or quarter-crack. Treads and barb-wire cuts are common injuries to the region of the coronet.
The preventive treatment consists in preserving a healthy condition of the horn by giving the foot the necessary care and attention in the way of proper trimming and shoeing, and providing it with the necessary moisture by means of foot-baths, wet clay and poultices. Quarter-cracks respond to treatment more quickly than toe-cracks. The treatment is practically the same for both. This consists in preventing motion in the margins of the fissure so far as possible.
[Illustration: FIG. 41.—Toe-cracks.]
[Illustration: FIG. 42.—Quarter-crack caused by barb-wire cut.]
The treatment for fissures in the region of the toe and quarter is as follows: The wall should be cut away along the margins of the crack until it is quite thin; and extra nail holes should be made in the shoe, and a nail driven into the bearing margin of the wall a little to each side of the fissure. The wall at the toe should be shortened and the toe of the shoe rolled if the animal's work permits the use of this kind of a shoe.
The margins of a quarter-crack and the wall just posterior and below it should be cut away until quite thin. The bearing margin should then be trimmed so that it does not rest on the shoe. A bar shoe that does not press on the frog may be used. Light blisters to the region of the coronet help in stimulating the growth of the horn. Rest is advisable.
CORNS.—This term is applied to injuries to the foot caused by bruises or continuous pressure to the posterior portion of the sole. This condition is common in the forefeet.