blood tumors, abscesses and pus fistulae that may be present in the region
of the poll and withers (Fig. 60). Pus fistula is the characteristic lesion
present, and it is the result of a suppurative inflammation of the tissues
in the region. The abscess cavity or cavities are usually deep, and may
involve the ligaments and vertebrae.

Bruises or contusions are the most _common causes_. The prominence of these
regions predisposes them to injury in the stable, or when rolling on rough
or stony ground. Bites and bruises to the withers resulting from other
horses taking hold of the region with the teeth, or striking the part
against a hard surface, are frequent causes.

_The treatment_ is both preventive and surgical. All possible causes should
be investigated. This is of special importance on premises where several
horses develop fistulous withers and poll evil. If the cause then becomes
known, it should be removed.

_The surgical treatment_ consists in opening up the different abscess
cavities, providing complete drainage for the pus and destroying the tissue
that lines the walls of the cavities. Horses that are prone to rub the
region should be prevented from doing this, as such irritation retards
healing. Autogenous bacterins should be used in addition to the surgical
treatment. A pus fistula should heal from the bottom, and if the opening
becomes closed, drainage should be re-established. The daily treatment is
the same as recommended for abscesses. Excessive cutting and destruction of
the tissues with caustic preparations result in scarring and deformity of
the part. Such radical lines of treatment should be discouraged. We should
not delay the surgical treatment of abscesses in the regions of the poll
and withers.