NAVICUL ARTHRITIS. 
543 
articular cartilage the same as the lower, has not, on any occasion 
whatever, been found a participator in the disease. “ I have fre- 
quently seen,” says Mr. Turner, “ in long-standing cases of navi- 
cular disease, not only all the cartilage of the inferior surface of 
the bone ulcerated, but also a material part of this small bone 
absorbed — almost annihilated — and yet found its upper surface 
sound, with the cartilage entire, and the synovial membrane quite 
perfect.” 
The MORBID APPEARANCES*presented by the navicular bursa 
of a horse who during life had been the subject of lameness from 
navicular disease, will vary according to the stage the disease 
happens to be in at the time of the horse’s death, and will also be 
influenced by the treatment the animal may have undergone for it 
during his life. It is only by chance that, in the early stages of 
navicularthritis, opportunities offer for post-mortem inspections ; 
though in the latter or groggy stages opportunities abound: it being 
any thing but a rare circumstance for an unfortunate wight of a 
horse to be led to the slaughter-house on the very account of his 
grogginess. 
That the disease at its outset, in its most active form, consists 
in inflammation, we have every evidence we can have to shew, 
considering the buried situation of the navicular bursa, and con- 
sidering that the inflammation itself, at its highest, is no more than 
what we should, comparing it with other inflammations, denominate 
sub-acute. Exceptions, however, must be made of such cases as 
occur on a sudden — where the horse, perfectly sound the moment 
before, and never lame at any antecedent period, falls lame in a 
moment ; for in such cases inflammation has had no time to set 
in to occasion the lameness; though it speedily supervenes in the 
injured tissues, and, subequently, itself becomes, if not the sole, 
a highly aggravated cause of the lameness. The probability is — 
for we can only through some mere accidental occurrence put it to 
the proof — that lameness occurring thus suddenly proceeds from 
lesion or actual breach of the synovial membrane of the navicu- 
lar bursa, and that either the crest upon the navicular bone, or the 
depression in the tendon opposite to it, is the seat of such lesion. 
At the same time it is to be presumed, that such injury — what- 
ever it may be — is intense of its kind, from the fact of its producing 
at once a limping lameness. 
A case related by the late Mr. Henderson, of Edinburgh, in the 
second volume of The Veterinarian, will be found to furnish 
us with some light hereupon. The horse had been lame from 
ossific inflammation of the cartilage of his left fore foot ; but had 
been restored to soundness, and continued sound for three years, 
when he fell lame again in the same foot. This time, however, 
