- 502 _DISEASES OF THE HORSE.. .. 
escape. After this, and whether we have found matter or not, we 
must induce an active inflammation of the tumor, in order to pro- 
mote solution of the thick walls of the abscess. This may be done by 
inserting well into the incision a piece of oakum or cotton saturated 
with turpentine, carbolic acid, tincture of iodin, etc., or we may pack 
the incision with powdered sulphate of zinc and keep the orifice 
plugged for 24 hours. These agents set up a destructive inflamma- 
tion of the walls. Suppuration follows, and this should now be en- 
couraged by hot fomentations and poultices. The orifice must be 
kept open, and should it be disposed to heal we must again introduce 
some of the agents above described. A favored treatment with many, 
and it is probably the best, is to plunge a red-hot iron to the bottom 
of the incision and thoroughly sear all parts of the walls of the ab- 
scess. This is to be repeated after the first. slough has taken place if 
the walls remain thickened and indurated. 
It is useless to waste time with fomentations, poultices, or blisters 
in the treatment of cold abscesses, since though apparently removed 
by such methods, they almost invariably return when the horse is 
put to work. Extirpation by the knife is not practicable, as the 
walls of the tumor are not sufficiently defined. If treated as above 
directed, and properly fitted with a good collar after healing, there 
will not remain any track or trace of the large, unsightly mass. 
FISTULAS. 
Definition—The word fistula is applied to any ulcerous lesion 
upon the external surface of the body which is connected by ducts, 
or passages, with some internal cavity. Because of this particular 
formation the term fistulous tract is often used synonymously with 
the word fistula. Fistulas may exist in any part of the body, but the 
name has come to be commonly accepted as applicable only to such 
lesions when found upon the withers. Poll evil is a fistula upon the 
poll, and in no sense differs from fistulous withers except in location. 
The description of fistula will apply, then, in the main, to poll evil 
equally well. Quittor presents the characteristic tubular passages of 
a fistula and may, therefore, be considered and treated as fistula of 
the foot. Fistulous passages may also be developed upon the sides 
of the face, through which saliva is discharged instead of flowing 
into the mouth, and are called salivary fistulas. A dental fistula may 
arise from the necrosis of the root of a tooth. Again, a fistula is 
sometimes noted at the umbilicus associated with hernia, and recto- 
vaginal fistulas have been developed in mares, following difficult 
parturition. Fistulas may arise from wounds of glandular organs 
or their ducts, and thus we have the so-called mammary or lacrimal 
fistulas. 
