396 DISEASES OF THE HORSE’S FOOT 
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 crepita- 
tion, 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 lame- 
ness that is at times excessive. But with the lameness 
there is nothing distinctive. The foot is tender on per- 
cussion, 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 ccronet, 
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, how- 
ever, 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 ap- 
proaches 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 por- 
tion, with its effect of giving greater length to the extensor 
pedis, leads to a backward displacement of the os corone 
