302 THE DISEASES OF THE FOOT. 



connexions with the coffin-bone, the navicular bone, and the flexor tendon, and are 

 thus perfectly secured. 



Below are other cartilages connected with the under edges of the former, and on 

 either side of the frog. 



Between these cartilages is the sensible frog, filling up the whole of the space, and 

 answering several important purposes, being an elastic bed on which the navicular 

 bone and the tendon (see page 272) can play with security, and without concussion 

 or shock, by which all concussion communicated to the cartilages of the foot are 

 destroyed — by which these cartilages are kept asunder, and the expansion of the upper 

 jart of the foot preserved. As the descent of the sole increases the width of the lower 

 part of the foot, so the elevation of the frog, a portion of it being pressed upward and 

 outward by the action of the navicular bone and tendon, causes the expansion of its 

 upper part. Precisely as the strong muscle peculiar to quadrupeds at the back of the 

 eye (see page 86), being forcibly contracted, presses upon the fatty matter in which 

 the eye is embedded, which may be displaced, but cannot be squeezed into less com- 

 pass, and which, being forced towards the inner corner of the eye, drives before it that 

 importgint and beautiful mechanism the haw, so the elastic and yielding substance the 

 frog, being pressed upon by the navicular bone and the tendon, and the pastern, and 

 refusing to be condensed into less compass, forces itself out on either side of them, 

 and expands the lateral cartilages, which again, by their inherent elasticity, recur to 

 their former situation, when the frog no longer presses them outward. It appears, 

 that by a different mechanism, but both equally admirable, and referable to the same 

 principle, viz. : that of elasticity, the expansion of the npper and lower portions of 

 the hoof are effected, the one by the descent of the sole, the other by the compression 

 and rising of the frog. 



It is this expansion upward, which contributes principally to the preservation of 

 the usefulness of the horse, when our destructive methods of shoeing are so calculated 

 to destroy the expansion beneath. In draught-horses, from the long-continued as well 

 as violent pressure on the frog, and from the frog on the cartilage, inflammation is 

 occasionally produced, which terminates in the cartilages being changed into bony 

 matter. 



CHAPTER XV. 



THE DISEASES OF THE FOOT. 



Of these there is a long list. That will not be wondered at by those who have 

 duly considered the complicated structure of the foot, the duty it has to perform, and 

 the injuries to which it is exposed. It will be proper to commence with that wiiich 

 is the cause of many other diseases of the foot, and connected with almost all. 



INFLAMMATION OF THE FOOT, OR ACUTE FOUNDER. 



The sensible laminse, or fleshy plates on the front and sides of the coffin-bone, being 

 replete with blood-vessels, are, like every other vascular part, liable to inflammation, 

 from its usual causes, and particularly from the violence with which, in rapid and 

 long-continued action, these parts are strained and bruised. When in a severely con- 

 tested race they have been stretched to their utmost, while, at the fullest stride of the 

 horse, his weight has been thrown on them with destructive force ; or, when the feet 

 have been battered and bruised in a hard day's journey, it will be no wonder if inflam- 

 mation of the over-worked parts should ensue, and the occurrence of it may probably 

 be produced and the disease aggravated by the too prevalent absurd mode of treating 

 the animal. If a horse that has been ridden or driven hard is suffered to stand in the 

 cold, or if his feet are washed and not speedily dried, he is very likely to have " fever 

 in the feet." There is no more fruitful source of inliannnatinn in the human being, or 

 the brute, than these sudden changes of temperature. This has been explained as it 

 regards grease, but it bears more immediately on the point now under consideration. 

 The danger is not confined to change from heat to cold. Sudden transition from cold 

 to heat is as injurious, and therefore it is that so many horses, after having been ridden 



