described under Fractures of the Os Pedis. It
appears, however, that other cases of the kind arise in which fracture is
altogether absent, or in which it is plainly seen to be subsequent to the
diseased processes in the bone. For that reason, and also for the reason
that the condition has come to be known by the name we have given, we give
it special mention.

_Symptoms and Diagnosis_.--Even when the condition arises as the result
of fracture, the ordinary manifestations of such a lesion are absent. By
reason of the situation of the parts within the hoof we are unable to
detect crepitation, and the resulting lameness is perhaps--in fact, nearly
always is--neglected until such time as any heat or swelling caused by the
injury has disappeared, in which case we are denied what evidence we might
have obtained from that. All that is presented is lameness, and lameness
that is at times excessive. But with the lameness there is nothing
distinctive. The foot is tender on percussion, and the gait suggestive of
foot lameness, that is all. We are unable, therefore, to make an exact
diagnosis, and the condition goes for some time undetected.

Later, however, changes in the form of the hoof and the coronet begin to
appear. The skin of the coronet, especially in the region of the toe,
becomes more or less thickened and indurated, and the same remark applies
to the subcutaneous tissues. The most marked change, however, is the
alteration in the shape of the hoof. The wall protrudes at the toe in a
manner that has been termed 'buttress-like,' and has given to the condition
one of its names. This, of course, entirely alters the contour of the horny
box. From being more or less U-shaped, it approaches nearer the formation
of the letter V, the point of the V being at the toe.

In the later stages the coronary enlargement is plainly seen to be due to
an extensive formation of bone. It is, in fact, a reparative callus, and
the reason it reaches so large a size is probably to be accounted for by
the pull of the extensor pedis upon the detached pyramidal process. As
might be expected, this displacement of the fractured portion, with its
effect of giving greater length to the extensor pedis, leads to a backward
displacement of the os coronae upon the pedal bone. As a result there is a
marked depression at the coronet, the depression being heightened in effect
by the exostosis in front. Pyramidal disease is, as a rule, met with in the
hind-feet