Fig. 61.—Groove for Charlier shoe formed by cutting away strip of wall.
Fig. 62.—Section of Charlier shoe on foot.
The Charlier System is a method of shoeing which a few years ago took a very prominent hold on the fancy of horse-owners. Like every other system it has advantages and disadvantages—it has prejudiced enemies and indiscreet friends. The principle or theory upon which it is based may be thus stated. The lower border of the wall is, it is said, the chief sustaining structure of the hoof, and as all that is required of a shoe is to prevent undue wear, therefore, remove a small strip of the lower border of the wall and substitute for it a similar sized strip of iron, and we shall protect from wear at the same time that we leave entirely to nature every other part of the hoof—sole, frog, and bars. This seems eminently simple and logical, but it is easy to show that it is more plausible than true. First, I would point out that the wall only is not the natural sustaining structure of the hoof. The wall and the sole at its connection with the wall is. Next I deny that the Charlier system does "leave entirely to nature every other part of the hoof." In cutting away the wall from the sole to affix the shoe, the natural function of the sole is seriously interfered with, and the bearing on the wall which ought to be partially distributed over the arch of the sole is limited to the wall. It is claimed that when the foot has had time to grow the sole will be found on a level with the shoe, and thus directly sharing in the weight-sustaining function. I have examined many feet shod by Charlier specialists, and have never yet seen the sole of a hind foot level with the shoe three days after the shoeing. Only once have I seen the sole of the fore foot level with the shoe after a week's wear. I am often apologetically told, "Well, it is not quite in wear, but it is not an eight of an inch below the surface of the shoe." Quite so, it is nearly in wear, but if not actually in wear what becomes of the principle? The sole is not directly in wear and bearing is confined to the wall. As to the frog, the Charlier affords no greater use to it than any other shoe of a similar thickness, unless instead of being placed on sound firm horn it be dangerously let down into the hoof so that its edge approaches very closely to the sensitive foot. It is sometimes difficult to arrive at the truth as to the significance of the phrase "embedding or letting down" the shoe of the Charlier system. At one time we are assured that "the shoe is not sunk, the sole is permitted to grow up." When this is so, very little positive objection to the system can be taken, because the shoe then rests at the same level on firm horn as does any other narrow shoe; but then the frog takes no better bearing than in other systems and the superfluous growth of horn on the sole is of no value. When the shoe is really "let down" of course the frog does receive increased pressure—it is forced to share with the wall the primary function of sustaining weight instead of, as in nature, taking only a secondary share of such action. It does this at the expense of a shoe placed so close to the "quick" that if the upper and inner border of iron be not bevelled off, immediate lameness results. When the Charlier shoe was first introduced it was applied the full length of the foot, but it was found that when thinned by wear the heels spread and led to injury of the opposite leg or to its being trodden off. Now the Charlier is only applied like a tip round the front portion of the surface of the foot, and it therefore partakes of some of the advantages I have credited to tips. It is a very light shoe and only requires small nails to fix it securely, but as the shoe is only the width of the wall the nails have to be driven solely in the wall, and their position is open to the objection applying to all too fine nailing. The disadvantages of the Charlier are its being "let down" too near the quick, its limited bearing, and its fine nail holes; the advantages are the lightness and the freedom given to the back of the foot, both of which are attainable with a narrow tip not let down. One very apparent effect resulting from the use of the Charlier system is the alteration in the action of the horse. All knee action is lost, and some horses go decidedly tender whilst others acquire a low shooting stride, which is certainly not in accordance with our notions of good free locomotion.
Fig. 63.—Groove for modified or short Charlier.