59 
LAMENESS IN THE FEET OF HORSES. 
injury from the very material which Nature bestowed as a de¬ 
fence, and which has degenerated into a hard, rigid, inelastic 
protuberance, no longer capable of yielding and expanding under 
the superincumbent weight. Nature has made ample provision 
to ward off concussion from these parts in the colt or unshod foot; 
for not only are the posterior parts much more elastic, as com¬ 
pared with the toe and sides of the foot, but she has also bolster¬ 
ed the navicular joint with two elastic cushions placed one on the 
other, and which, united, form such a hard and soft medium, as 
no human ingenuity could imitate. The tough, though highly 
elastic, homy frog being opposed to the ground j and the tatty 
fro op encompassing the navicular bone and flexor tendon, which 
are 5 further shielded by elastic cartilages. Now, as all these 
parts, in a state of nature, preserve their elastic properties, they 
yield and give room for the navicular joint to play like a pulfoy, 
without compression or restraint, in the most violent exertions ot 
the animal. , . 
I am thoroughly satisfied, that, when contraction is accorn- 
panied with chronic lameness, disease exists in the navicular joint, 
either structural or functional; and that tins complaint, at its 
commencement, is neither more nor less than a braise ot the 
synovial membrane lining the joint. . . . 
" Although it appears that some degree of violence is essential 
to the completion of this formidable disease, yet I am convinced 
that it does not originate in wear and tear, from contact with 
either the roads of the former or present day: it has, m rea. 
truth, its origin in rest. It is certainly engendered in the stable, 
but becomes permanently established by sudden violence out of 
the stable: and I have frequently observed, that, under peculiar 
pre-existent circumstances, a very moderate proportion of exei- 
tion on a hard road or stones has been quite sufficient. 1 wo 01 
three severe days’ work in succession, immediately aftei long 
continued confinement in a stall, and the hurried pace and dis¬ 
tance united, would compel the animal eventually (though per¬ 
haps against his will) to convey lus weight abruptly, and with 
considerable force, on this obstructing body formed by a fixed 
elevation of the frog in conjunction w r ith a morbidly thick sole. 
The experience of several years practice has convinced me 
that this delicate membrane does not, in the majority of ca^es, 
receive the shock from the ground or from stones, as I was 
inclined to think when I first saw the navicular disease; but my 
opinion remains unaltered with regard to the diseased 01 inflamed 
navicular joint being the source of pain, and actual cause of 
lameness. And I am still of opinion, that cases do often occui 
