NAVICULAR-JOINT DISEASE. 309 



shoe again applied, and the horse had returned to his work, than the heels hegan to 

 narrow, and the foot became as contracted as ever. Common sense would have 

 foretold that such must have been the result of this expansive process; for the heels 

 could have been only thus forced asunder at the expense of partial or total separation 

 from the interior portions of the foot with which they were in contact. 



The contracted heel can rarely or never permanently expand, for this plain reason, 

 that although we may have power over the crust, we cannot renew the laminae, or 

 restore the portion of the frog that has been absorbed. 



If the action of the liorse is not materially impaired, it is better to let the contrac- 

 tion alone, be it as great as it will. If the contraction has evidently produced consi- 

 derable lameness, the owner of the horse will have to calculate between his value if 

 cured, the expense of the cure, and the probability of faihire. 



The medical treatment should alone be undertaken by a skilful veterinary surgeon, 

 and it will principally consist in abating any inflammation that n.-ay exist, by local 

 bleeding and physic, paring the sole to the utmost extent that it will bear; rasping 

 the quarters as deeply as can be, without their being too much weakened, or the 

 coronary ring (see b, p. 272) injured ; rasping deeply likewise at the toe, and perhaps 

 scoring at the toe. The horse is afterwards made to stand during the day in wet 

 clay, placed in one of the stalls. He is at night moved into another stall, and his 

 feet bound up thickly in wet cloths ; or he is turned out into wet pasturage, with tips, 

 or, if possible, without them, and his feet are frequently pared out, and the quarters 

 lightly rasped. In five or six months the horn will generally have grown down, 

 when he may be taLen up, and shod with shoes unattached by nails on the inner side 

 of the foot, and put to gentle work. The foot will be found very considerably enlarged, 

 and the owner will, perhaps, tliink that the cure is accomplished. The horse may, 

 possibly, for a time stand very gentle work, and the inner side of the foot being left 

 at liberty, its natural expansive process may be resumed : the internal part of the foot, 

 however, has not been healthily filled up with the expansion of the crust. If that 

 expansion has been effected forward on the quarters, the crust will no longer be in 

 contact with the lengthened and narrowed heels of the coffin-bone. There will not be 

 the natural adhesion and strength, and a very slight cause, or even the very habit of 

 contraction, will, in spite of all care and the freedom of the inner quarter, in very 

 many instances, cause the foot to wire in again as badly as before. 



THE NAVICULAR-JOINT DISEASE. 



Many horses with well-formed and open feet become sadly and permanently lame, 

 and veterinary surgeons have been puzzled to discover the cause. The farrier has had 

 his convenient explanation "the shoulder;" but the scientific practitioner may not 

 have been able to discover an ostensible cause of lameness in the whole limb. There 

 is no one accustomed to horses who does not recollect an instance of this. 



By reference to the cut, e, page 272, it will be seen that, behind and beneath the 

 lower pastern-bone, and behind and above the heel of the coffin-bone, is a small bone 

 called the navicular or shuttle bone. It is so placed as to strengthen the union between 

 the lower pastern and the coffin-bone, and to enable the flexor tendon, which passes 

 over it in order to be inserted into the bottom of the coffin-bone, to act with more 

 advantage. It forms a kind of joint with that tendon. There is a great deal of weight 

 thrown on the navicular-bone, and from the navicular-bone on the tendon ; and there 

 is a great deal of motion or play between them in the bending and extension of the 

 pasterns. It is very easy to conceive that, from sudden concussion, or from rapid and 

 overstrained motion, and that, perhaps, after the animal has been sometime at rest, 

 and the parts have not adapted themselves for motion, there may be too much play 

 between the bone and the tendon — the delicate membrane which covers the bone, or 

 the cartilage of the bone, may be bruised, and inflamed, and destroyed ; that all the 

 painful effects of an inflamed and opened joint may ensue, and the horse be irreco- 

 verably lame. Numerous dissections have shown that this joint, formed by the tendon 

 and the bone, has been the frequent, and the almost invariable, seat of these obscure 

 amenesses. The membrane covering the cartilage of the bone has been found in an 

 ulcerated state ; the cartilage has been ulcerated and eaten away ; the bone has become 

 carious or decayed, and bony adhesions have taken place between the navicular and 

 the pastern and the coffin-bones, and this part of the foot has often become completely 

 disorganised and useless. This joint is probably the seat of lameness, not only Iti 



