424 IOWA DEPARTMENT OF AGRICULTURE 
be well fitted, neither too large nor too small, and it should be cleaned 
and oiled to remove all dirt and to make it soft and pliable. Saddles 
should be properly fitted so as to prevent direct pressure on the spine, 
and the saddle blankets should be clean and dry. Parts of the horse 
where chafing is likely to occur, as on the back under the saddle, should 
be cleaned and brushed free of dirt. 
The remedies for simple harness galls are numerous. Among them 
may be mentioned alcohol, 1 pint, in which are well shaken the whites 
of two eggs; a solution of nitrate of silver, 10 grains to the ounce of 
water; sugar of lead or sulphate of zinc, 20 grains to an ounce of water; 
carbolic acid, 1 part in 15 parts of glycerin, and so on almost without 
end. Any simple astringent wash or powder will effect a cure, provided 
the sores are not irritated by friction. 
If a sitfast has developed, the dead horn-like slough must be carefully- 
dissected out and the wound treated carefully with antiseptics. During 
treatment it is always best to allow the animal to rest, but if this is 
inconvenient care should be taken to prevent injury to the abraded or 
wounded surface by padding the harness so that chafing can not occur. 
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 com- 
monly 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 char- 
acteristic tubular passages of a fistula and may therefore be considered 
and treated as fistula of the foot. Fistulous passages may also be de- 
veloped upon the sides of the face, th'rough 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 lachrymal, 
fistulas. 
Fistulous tracts are lined with a false, or adventitious, membrane and 
show no disposition to heal. They constantly afford means of exit to the 
pus or ichorous material discharged by the unhealthy parts below. They 
are particularly liable to develop at the withers or poll because of the 
exposed position which these parts occupy, and, having once become lo- 
cated there, they usually assert a tendency to further extension, because 
the vertical and laminated formation of the muscles and tendons of these 
parts allows the forces of gravitation to assist the pus in gaining the 
deeper lying structures and also favors its retention among them. 
