452 DISEASES OF THE HORSE. 
selves are irregular and granular in appearance. Pumiced sole de- 
pends upon an impairment of the horn-secreting powers of the sensi- 
tive sole or upon a separation of the horny from the soft tissues 
which maintain its vitality. 
Punctured wounds of the foot, accompanied with any considerable 
destruction of the soft tissues, present the same peculiarities of horn 
in the immediate neighborhood of the injury. Bruises of the sole are 
followed by this change when the exudation has been excessive and 
has separated the horn from the living tissues. True, in these cases 
we rarely see the soft tissues laid bare, for the reason that new horn 
is constantly secreted and replaces that undergoing disintegration. 
Laminitis 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 pro- 
duction of horn by impairing or destroying the horn-secreting mem- 
brane; second, when depression of the coffin bone causes pressure 
upon and arrests the formation of horn; and, third, when the eleva- 
tion 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 
