is presents three conditions under which pumiced sole may appear:
First, when free exudation separates the horn from the other tissues, or
when the process of inflammation arrests the production of horn by
impairing or destroying the horn-secreting membrane; second, when
depression of the coffin bone causes pressure upon and arrests the
formation of horn; and, third, when the elevation of the sole compresses
the soft tissues against the pedal bone and induces the same condition.

Pumiced sole, from simple exudation and separation of tissues, is of
little importance for the reason given above in connection with bruises;
but when suppuration occurs in restricted portions of the foot in
conjunction with laminitis, it always lays bare the tissues beneath and
temporarily impairs the animal's value. Recovery takes place after a few
weeks by the tissues "horning over," as in injuries attended by the same
process. Depression of the coffin bone is not sufficient within itself
to cause pumiced sole; for, if the relative change in the bone takes
place slowly, or if the horn is thin, the sole becomes convex from
gradual pressure and the soft tissues adapt themselves to the change
without having their function materially impaired. But when the dropping
is sudden and the soft tissues are destroyed, the horn rapidly crumbles
away and the toe of the bone comes through. In many of these cases the
soft tissues remain uncovered for months. When they are eventually
covered it is with a thin, slightly adherent horn that stands but little
or no wear. The sole being now convex, the diseased tissues bear unusual
weight by coming in contact with the ground, and hence it is that these
animals are generally incurable cripples.

In most cases in which the sole is raised to meet the pedal bone and
pumiced sole occurs it is due not to pressure of the bone from within
(for the tissues are capable of adapting themselves to the gradual
change) but to impaired vitality of the sensitive tissues from the
inflammation and to the constant concussion and pressure applied from
without during progression. To this is to be added the paring away of
the horn when applying the shoe, thereby keeping the sole at this point
too thin.

_Turning up of the toe._--In many cases of laminitis which have become
chronic it is found that the toe of the foot turns up; that the heels
are longer than natural; while the hoof near the coronary band is
circled with ridges like th