152 ON THE NAVICULAR DISEASE AND SPAVIN. 
coronet diminishing, it requires no very extraordinary talent in an 
experienced practitioner to discover the seat of the malady, 
though it would puzzle all his tact and discrimination to effect a 
radical cure, if the disease have existed any length of time. 
My attention was struck with the feasibility of a theory offered 
by Mr. Turner as to one cause of the navicular disease, and I 
cannot divest myself of the idea, that such a cause, oftener than 
any other, produces it. I allude to what he has said about the 
condition of the foot in horses confined, as they usually are, to a 
stall for four or five days together. The horse, in a state of 
nature, seeking his food, is always upon the move; consequently 
the frog and posterior part of the foot are in motion, and by 
means of that motion retain their wonted elasticity : not so in 
his artificial state, tied to the manger, for the frog then becomes 
hardened, and is in itself the cause of violence to a part,—the 
navicular joint,—which it was purposely designed to protect. 
The animal, after so long a rest, is taken out of his stable, and, 
perhaps, hurried immediately into a quick pace: the result is, 
that mischief to the foot is accruing at every step, in consequence 
of the weight of the animal squeezing the tendon between the 
navicular bone and the frog. The short step and the stumble of 
a horse just starting corroborate the truth of this reasoning; and 
I have also observed that the disease occurs oftener in those feet 
where the frog is inclined to be protuberant and hard, than when 
it is smaller in size and preserves its elasticity. 
All horses prefer standing with their heels elevated ; and when¬ 
ever there is a favourable opportunity, such as a shelving grating 
in the middle of the stall, we invariably find them back in their 
places to enjoy such a position. This posture is no doubt pre¬ 
ferred to the opposite one, inasmuch as it relieves the flexor 
muscles and tendons from the weight which appears to be borne 
with less stress to the animal by the laminae and extensors ; but 
it also favours the ascent of the frog and sole, which, by long 
rest, have become fixed in this elevated position, when it only 
requires, as Mr. Turner has it, a trot over the stones to Mile End 
to produce a navicular case. I contend that we have more cases 
commencing in this way than when the disease has been coming 
on gradually, or treacherously, for a long time before it has been 
discovered; and that the symptoms described by Mr. Turner as 
antecedent, usually occur subsequently to the affection of the 
joint. 
To account for the many injurious alterations that take place in 
the foot of the horse, I must refer you to the difference between the 
shod and the unshod hoof. The foot of a horse at grass is always 
filled with earth, which affords a necessary degree of support to 
