e outward signs are wanting,
however, and the true nature of our case is a matter of mere conjecture, a
positive diagnosis may still be made at a later stage--that is, when the
abnormal growth of horn reaches the sole. In this case either there is
met with when paring the sole a small portion of horn, circular in form,
distinctly harder than normal, and indenting in a semicircular fashion the
front of the white line at the toe, or solution of continuity between the
tumour and the edge of the sole and the os pedis takes place, and the
lameness resulting from the ingress of dirt and grit thus allowed draws
attention to the case.

_Pathological Anatomy_.--With the sensitive structures removed from the
hoof by maceration or other means, these growths are at once apparent. They
may occur in any position, but are usually seen at the toe, and they may
extend from the coronary cushion to the sole, or they may occupy only
the lower or the upper half of the wall. In places the tumour (or 'horny
pillar' as the Germans term it) is roughened by offshoots from it, and does
not always exhibit the smooth surface depicted in Fig. 132. Commonly, the
horn composing the new growth is hard and dense. Sometimes, however, it is
soft to the knife, and is then found to be itself fistulous in character,
a distinct cavity running up its centre, from which issues a black and
offensive pus.

In a few cases the sensitive laminae in the immediate neighbourhood are
found to be enlarged, but in the majority of cases atrophy is the condition
to be observed. Not only are the sensitive structures found to be shrunken
and absorbed, but the atrophy and absorption extends even to the bone
itself (see Fig. 133). This latter is a result of the continued pressure of
the horny growth, in a well-marked case ending in a sharply-defined groove
in the os pedis in which the keraphyllocele rests. The fact that the softer
structures, and even the bone, thus accommodate themselves to the altered
conditions is, no doubt, the reason that lameness in many of these cases is
absent.

_Treatment_.--It is doubtful whether anything satisfactory can be
recommended. When we have suspected this condition ourselves, it has been
our practice to groove the hoof on either side of the toe, after the manner
illustrated in Fig. 120, and, at the same time, point-firing the coronet
and applying a smart cantharides blister. Certainly, after this operation,
lameness has often disappeared--