298 THE HORSE. 



THE NAVICULAR-JOINT DISEASE. 



Many horses with well-formed and open feet become sadly and perma- 

 nently lame; and veterinary surgeons have been much puzzled to hnd out 

 why. The farrier has liad his convenient explanation "the slioulder;" but 

 the scientific practitioner has not been able to discover an ostensible cause 

 of lameness in the wiiole limb. There is no one accustomed to iiorses who 

 does not recollect many an instance of this. Mr. James Turner has, of 

 late years, thrown very considerable light on the seat and cause of thisdis. 

 ease, although, as in contracted feet, the most skilful surgeon will rarely 

 effect a cure. 



By reference to our cut, (e, page 249,) it will be seen that, behind and 

 beneath the lower pastern-bone, and behind and above the heel of tiie 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 

 ihe 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 exten- 

 sion of the pasterns. Now, it is very easy to conceive that, from sudden 

 concussion, or from rapid and overstrained motion, and that perhaps after the 

 animal has been some time at rest, and the parts have not adapted them- 

 selves for motion, that there may be too much play between the bone and 

 the tendon ; that the delicate membrane which covers the bone, or the car- 

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

 all the painful effects of an inflamed and opened joint may ensue, and the 

 horse may be dreadfully lame. Numerous dissections have shown that this 

 joint, formed by the tendon and the bone, has been the frequent, and, we 

 believe it to be, the almost invariable seat of these obscure lamenesses. 

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

 ulcerated state; the cartilage itself has been ulcerated and eaten away; 

 and the bone has become carious or decayed, and bony adiiesions have often 

 taken place between the navicular and the pastern and the coffin-bones, and 

 this part of the foot has become completely disorganized and useless. 

 This joint is probably the seat of lameness, not only in flat and perfect feet, 

 but in those which become lame after contraction ; for in proportion as the 

 inner frog is compressed by the contraction of the heels, and the frog is 

 absorbed by that pressure, and the sole is become concave, and the horny- 

 frog, and the coffin-bone too, thereby elevated (see cut, page 269), will 

 there be less room for the action of this joint, and more danger of the ten-, 

 don and the delicate membrane of the navicular-bone being crushed between 

 that bone and the horny frog. 



Stable management has little to do with the production of this disease, 

 any further than if a horse stands idle in the stable several days, and the 

 structure of the foot, and all the apparatus connected with motion, become 

 unused to exertion, and indisposed for it, and he be then suddenly and 

 violently exercised, this membrane is very liable to be bruised and injured. 

 Irregular and undue exercifje are the causes in all feet; but the contracted 

 foot, from its alteration of form, is most in danger. 



The cure is extremely uncertain. The first object is to abate tlie inflam- 

 mation in this very susceptible membrane. Local bleeding, poulticing, 

 and physic will be our principal resources. If there be contraction, this 

 ninsl, if possible, be removed by the means already pointed out. If there 

 be n:)t contraction, it will be prudent to remove all surrounding pressure 



