The toeing knife cannot leave a finished level bearing surface, and its work has to be completed by a few strokes of the rasp. A farrier should, therefore, never attempt to remove all the superfluous horn with the knife, he should leave some for the rasp so that in producing the final level surface no encroachment upon the necessary thickness of covering horn need be made.
Fig. 18.
The overgrown foot such as we find on a healthy horse that has retained a set of shoes for some weeks, or that has been without shoes on a surface not hard enough to cause sufficient wear, is quite unfitted to receive a shoe. It must be reduced to proportions. In [Fig. 18], I have attempted to show diagrammatically a side view of an overgrown hoof. The dotted lines at the base show two effects of lowering one part more than another, although both attain a level surface. In [Fig. 21] we see the result of over-lowering the heels, and in [Fig. 20] of leaving them too high. It may also be noticed that these conditions affect other parts of the foot; in fact not only other parts but the whole foot, and even the relative position of the foot to the leg. If we compare the proportionate foot, [Fig. 19], with the diagram [Fig. 21], it will be seen that by over-lowering the heels the slope of the front of the foot is increased, that the bearing surface from heel to toe is slightly increased in length, and that if the dotted perpendicular line be accepted as showing the direction through which the weight of the body passes, lowering the heels tends to put an increased proportion of weight on the back parts of the foot. If we compare [Fig. 19] with [Fig. 20] we see the effect of leaving the heels too high. The bearing surface from heel to toe is shortened, the slope of the wall at the toe is made less, and more weight is thrown upon the front parts of the foot.
Fig. 19.—A proportionate hoof.
