Turning in of the Wall. By this expression, I mean those cases of weak low-heels in which the border of the wall turns inward. Such a form of horn offers no suitable bearing for a shoe, and if submitted to pressure by a shoe gets worse. Too often this condition is treated by paring away the sole within, which increases the deformity. The sole should not be cut but be left as strong as possible. The curled-in border of the wall should be cut down and all bearing taken off the shoe. In one or two shoeings the wall will resume its proper form. When both heels are so affected, and the horse has to remain at work, only one heel must be treated at a time. The extreme point of the heel is never affected, and affords a point for bearing when the border of wall in front of it is cut away so as not to touch the shoe.
[CHAPTER X.]
Leather and Rubber Pads.
In the days when farriers were driven by theoretical teachers to pare out the soles and otherwise rob the foot of its natural covering of horn, artificial protection had frequently to be given to the foot. A horse with a thin sole could not travel over rough roads, on which sharp loose stones were plentiful, without great risk of injury; consequently in those times plates of leather were often used to protect the foot. When a horse went "a little short" his owner not unnaturally concluded that he had bruised his foot and that the protection of a leather sole would be beneficial. In many cases the defective action was due to other cause than bruising, but still the leather was adopted, and it soon became an accepted theory that leather soles modified concussion and protected the foot from jar. This is more than doubtful, and I hold a very firm opinion that a plate of leather between the shoe and the foot has no such effect, whilst it interferes with the exactness of fit of the shoe. "Leathers" are useful on weak feet to protect a thin or defective sole from injury. When the under surface of a foot has been bruised, cut through, or when it is diseased, leather offers a useful protection, but when the sole is firm and sound it is quite unnecessary.
To apply leather properly, a square piece fully the size of the shoe is taken. A portion is then cut out where the clip has to fit and all protruding parts cut away level with the border of the shoe. If applied without more precautions, an open space would be left between leather and sole into which mud and grit would find their way and the leather would soon be cut through by resting on the irregular surface of the frog. To prevent this mischief the under surface of the foot is made level before the shoe is applied. The leveling is managed by spreading a paste of tar and oatmeal over the sole, and filling up the space at the sides of the frog with tow. Then the shoe with the leather is nailed on in the usual manner.
The belief in leather as an anti-concussive appliance has led to the use of what are called "ring-leathers." These are not plates covering the whole under surface of the foot but narrow bands fixed between shoe and hoof. They are absolutely useless, in fact their only possible effect is to spoil the fit of the shoe. Plates of india-rubber have been tried between the shoe and the foot as preventives of concussion. They invariably fail by reason of their effect upon the shoe. At each step when the weight of the horse comes on the foot the elastic rubber yields, the shoe is pressed closer to the foot, the nails are loosened, and when the foot is raised the rubber rebounds. The shoe soon becomes so loose that it is cast or torn off. Nothing elastic should be placed between shoe and foot. When an elastic or spring is applied it must be between the shoe and the ground.
Various arrangements have been adopted to supply the horse's foot with some provision against concussion. Injured and diseased feet may no doubt be benefitted by some elastic appliance which secures them from the jar of contact on a hard road. They may be protected against direct bruise. The healthy foot requires no such protection. Nature has covered it with a thick layer of horn and has provided against concussion by quite other means—by the co-ordinate action of muscles, by the oblique position of the pastern and by the construction of the back part of the foot.
Quite apart from any attempt to prevent concussion a valuable use has been found for india-rubber pads in connection with horse-shoeing. The improvement in modern road-surfaces has been accompanied by an increased facility for slipping, and it has been found that no material gives such security of foot-hold on smooth surfaces as india-rubber.
The earliest of these contrivances with which I am acquainted was formed so as to leave the frog uncovered whilst a bearing of rubber was given all round the inner circumference of the shoe. This pad had a wide flat border which fitted under the shoe, with which it was nailed on to the foot. Its great objection was that it could not be nicely fitted on many feet without first cutting away the bars.