Fig. 51.—Section of a seated shoe.
For flat feet a wide shoe with a flat foot-surface is unsafe as there is liability to uneven pressure on the sole. For such feet the safer form of foot-surface is one presenting a level narrow bearing-surface round its outer border, from which an inclined or bevelled surface continues the shoe inwards. ([Fig. 51]) This form of shoe can be fitted to nearly any kind of foot. To escape injury to a flat sole "seating out" shoes is necessary, but the operation should always leave a level bearing-surface for the wall. When a shoe is seated from one side to the other so as to produce a saucer shaped surface harm is done to the foot. Such a shoe presents no level bearing-surface, and the weight of the horse pressing the wall on an inclined plane causes the foot to be pinched or compressed in a manner which soon causes lameness. ([Fig. 52]). A few years ago these shoes were too common, and to make them still more injurious, the foot was pared out from the centre to the circumference like a saucer, and the two spoiled articles were fitted together. Their surfaces of contact were two narrow ridges which even the most expert workman could not fit without injury to the horse.
Fig. 52.—Section of a "saucer" shoe.
In [Fig. 52] a shoe with an inclined surface is applied to a foot with a bearing-surface as wide as the wall but the only contact is at the edges. The horn at the edge will yield, and the hoof be pressed inwards as the weight of the animal forces the foot into the saucer-shaped shoe. When the bearing-surface of the foot, instead of being as wide as the wall, is only a ridge, the horn yields more rapidly, the clinches rise and the shoe becomes loose.
In [Fig. 53] is shown a section of another shoe with an inclined instead of a level surface, but the slope is from within outwards. The effect of this is exactly the opposite of the previous shoe. The wall is forced outwards, and if it does not as a whole yield to the pressure the portion in contact is broken. When this form of bearing-surface is adopted at the heels of a shoe the two sides of the hoof are violently forced apart, and it has even been recommended as a means of expanding the foot; but forcible expansion is both unnecessary and dangerous.
Always regarding the shoe as an extension of the natural hoof in a harder and more durable material, it is evident that the most stability will be attained by the use of as wide a bearing-surface of foot and shoe as is compatible with ease and safety to the horse.
In [Fig. 54] is shown a section of a narrow shoe which takes a bearing over the whole extent of its foot-surface.