in well formed feet. Where
only one cartilage is ossified, the other being flexible, there is less
inconvenience experienced by the subject during weight-bearing, because
of the expansion of the heel which the one normal cartilage allows.

Treatment.--There is little if anything to be done in case the
cartilage has become ossified except to shoe without high calks but
preferably with rubber pads. The hoof should be kept moist; the wall at
the quarter may be rasped thin and kept anointed. Firing is of no
practical benefit in these cases, and it is doubtful if vesication is
helpful excepting where only a part of the cartilage is ossified.

Subjects which continue somewhat lame, because of complete ossification
of both cartilages, are best put to slow work on soft ground and not
driven on pavements.

Navicular Disease.

This more or less ambiguous term has been applied to various diseases
affecting the structures which make up the coffin joint. We consider
this name to be applicable to inflammatory involvement of the third
sesamoid (navicular bone), the deep flexor tendon (perforans) and the
bursa podotrochlearis or navicular bursa.

Etiology and Occurrence.--In 1864 Thomas Greaves[29] wrote on the
subject of navicular disease as follows: "The opinion I entertain upon
the subject of navicular disease is, that in by far the greater majority
(if not all) of these cases there exists in the animal affected a
congenital tendency or predisposition, that, generally speaking, it is
the high stepper, the good goer, that becomes the victim to this
disease; and it is a fact well attested, that it as frequently develops
itself in the feet with wide frogs, bulbous heels, shallow heels, spread
flattish feet, as in the narrow upright feet.... I have known foals,
born from defective parents, in which this condition was so strongly
developed, that all men would at once pronounce them affected with
navicular disease, and such lameness was permanent."

Often both fore feet are affected and this would point toward its being
a disease wherein either conformation or congenital tendencies exists.
It is rare that hind feet are involved.

There are many theories regarding the possible exciting causes of
navicular disease and, when one has carefully considered the
explanations as offered by Peters, Moeller, Branell, Schrader and others,
he may conclude that navicular disease is a non-infectuous inflammatory
affection of the third sesamoi