severe bruise or contusion that is followed by the infection of the part
with some of the pus-producing bacteria. Abscesses occur in certain
infectious diseases. In strangles, the disease-producing organism may be
carried to different regions of the body by the circulatory vessels. This
may result in a number of abscesses forming in the different body tissues.

The following _forms of abscess_ are recognized: hot and cold, superficial
and deep, simple and multiple. The hot is the acute, and the cold the
chronic abscess. The terms superficial and deep allude to the relative
position of the abscess, and simple and multiple to the number present.

An abscess may first appear as a hot, painful swelling. If superficial, the
skin feels tense and the contents fluctuate when pressed on. Later the
fever subsides and no pain may occur when the abscess is pressed upon. Deep
abscess may not fluctuate.

_The treatment_ consists in converting the abscess into an open wound
whenever possible. The incision should extend to the lowest part of the
wall, so as to insure complete drainage. A cold abscess in the shoulder
region may become lined by a layer of tissue that retards healing. In order
to hasten the healing process, it may be necessary to remove this. Until
granulation is well advanced, the abscess cavity should be irrigated daily
with a one per cent water solution of liquor cresolis compositus, or a one
to two thousand water solution of corrosive sublimate. The surface of the
skin in the region of the abscess should be kept clean.

[Illustration: FIG. 60.--Fistula of the withers, showing the effect of
using caustics carelessly.]

FISTULOUS WITHERS AND POLL EVIL.--These terms are applied to swellings,