296 THE FOOT. 



The foot is composed of the horny box that covers the extremities of the horse, and 

 the contents of that box. The hoof or box is composed of the crust or wall, the coro- 

 nary ring and band, the bars, the horny laminae, the sole, and the horny frog. 



THE CRUST OR WALL OF THE HOOF. 



The. crust, or wall, is that portion which is seen when the foot is placed on the 

 ground, and reaches from the termination of the hair to the ground. It is deepest in 

 front, where it is called the toe, measuring there about three inches and a half in 

 depth (see cut, p. 297), shallower at the sides, which are denominated the quarters, 

 and of least extent behind, where it is seldom more than an inch and a half in height, 

 and is termed the heel. The crust in the healthy foot presents a flat and narrow sur- 

 face to the ground, ascending obliquely backwards, and possessing different degrees 

 of obliquity in different horses. In a sound hoof the proper degree of obliquity is 

 calculated at forty-five degrees, or the fourth part of a semicircle, at the front of the 

 foot. When the obliquity is greater than this, it indicates undue flatness of the sole, 

 and the crust is said to have " fallen in." If the obliquity is very much increased, the 

 sole projects, and is said to be pumiced or convex. 



If the foot is more upright, or forms a greater angle than forty-five degrees, it 

 indicates much contraction, and a sole too concave ; and this difference of obliquity 

 is often so great, that the convexity or concavity of the sole may be affirmed without 

 the trouble of raising the foot for the purpose of examination. 



It is of some importance to observe whether the depth of the crust appears rapidly 

 or slowly to decrease from the front to the heel. If the decrease is little, and even at 

 the heel the crust is high and deep, this indicates a foot liable to contraction, sand- 

 crack, thrush, and inflammation. The pasterns are upright, the paces of that horse 

 are not pleasant. On the other hand, if the crust rapidly diminishes in depth, and 

 the heels are low, this is accompanied by too great slanting of the pastern, and dis- 

 position to sprain in the back sinew. The foot, generally, is liable to be weak and 

 flat, and bruised, and there is more tendency to the frequent, but obscure lameness, 

 of which there will presently be occasion to treat — the navicular-joint disease. 



The crust is composed of numerous horny fibres, connected together by an elastic 

 membranous substance, and extending from the coronet to the base of the hoof. It 

 differs materially in its texture, its elasticity, its growth, and its occasional fragility, 

 according to the state in which it is kept, and the circumstances that are acting 

 upon it. 



The exterior wall of the hoof should be smooth and level. Protuberances or rings 

 round the crust indicate that the horse has had inflammation in the feet, and that to 

 such a degree, as to produce an unequal growth of horn, and probably to leave some 

 injurious consequences in the internal part of the foot. If there is a depression or 

 hollow in front of the foot, it betrays a sinking of the coffm-bone, and a flat or pumiced 

 sole. If there is a hollow at the quarters, it is the worst symptom of bad contraction. 



The thickness of the crust, in the front of the foot, is rather more than half an inch; 

 it becomes gradually thinner towards the quarters and heels, but this often varies to 

 a considerable extent. In some hoofs, it is not more than half the above thickness. 

 If however there is not, in the majority of horses, more than half an inch for nail-hold 

 at the toe, and not so much at the quarters, it will not appear surprising that these 

 horses are occasionally wounded in shoeing, and especially as some of them are very 

 unmanageable while undergoing this process. 



\Yhile the crust becomes thinner towards both quarters, it is more so at the innei 

 quarter than at the outer, because more weight is thrown upon it than upon the outer. 

 It is more under the horse. It is under the inner splint-bone, on which so much more 

 of the weight rests than on the outer ; and, being thinner, it is able to expand more. 

 Its elasticity is called more into play, and concussion and injury are avoided. When 

 the expansion of the quarters is prevented by their being nailed to an unbending shoe, 

 the inner quarter suffers most. Corns are oftenest found there; contraction begins 

 there; sand-crack is seated there. Nature meant that this should he the most yield- 

 ing part, in order to obviate concussion, because on it the weight is principally 

 thrown, and therefore when its power of yielding is taken away it must be the first 

 to suffer. 



A careful observer will likewise perceive that the inner quarter is higher than the 



