, filling up the
cavity, the walls will become thickened and hard, resulting in the
formation of a tumor.

The elbow, the knee, and the hock are the parts of the body where these
lesions are ordinarily found, and on account of their peculiar shape and
the position they occupy they have received the denomination "capped."
They will be considered in their peculiar aspect.

CAPPED ELBOW.

Capped elbow, or "shoe boil," is a term applied to an enlargement often
found at the point of the elbow.

_Cause._--This lesion is due to injury or pressure of the part while it
is resting on the ground. The horse, unlike the cow, does not rest
directly on the under surface of the sternum, or breastbone, on account
of its sharp, ridge-like formation. He rests more on the side of the
breastbone and chest, and consequently the leg which is flexed under
the body is subject to considerable pressure. If the leg is flexed under
the body so that the hoof or shoe is directly in contact with the elbow,
which may occur in horses having an extremely long cannon bone or
excessive length in the shoes, the greater part of the weight of the
chest is concentrated at this point and the pressure may cause a bruise
or an inflammation.

_Symptoms._--Under these conditions the point of the elbow may become
swollen and tender and exhibit heat and pain. This swelling may not only
cover the point of the elbow, but sometimes reaches the axilla and
assumes such proportions that there is great difficulty in using the
leg, the animal showing signs of lameness even to the extent of the
circumflex step, as in shoulder lameness. This edematous condition,
however, does not remain stationary. It may by degrees subside or
perhaps disappear. In the first instance it will become more distinctly
defined, with better marked boundaries, until it is reduced to a soft,
round, fluctuating tumor, with or without heat or pain. There is then
either a bloody or serous tumor or a purulent collection, and following
the puncture of its walls with the knife there will be an escape of
blood, serum, or pus, as the case may be, in variable quantities. In
either case, but principally in that of the cystic form, the tumor will
be found to be subdivided by septa, or bands running in various
directions.

Various changes will follow the opening of the tumor and the escape of
its contents. In a majority of cases the process of cicatrization will
take place, and the cavity fill up by gra