e caustic is
introduced from irritating or blistering the skin over which it flows.
In obstinate cases a piece of caustic potash (fused) 1 to 2 inches in
length may be introduced into the opening and should be covered with
oakum or cotton. The horse should then be secured so that he can not
reach the part with his teeth. After the caustic plug has been in place
for 24 hours, it may be removed and hot fomentations applied. As soon as
the discharge has become again established the abscess should be opened
from its lowest extremity, and the passage thus formed may be kept open
by the introduction of a seton. If the pipes become established in the
deep tissues beneath the shoulder blade or among the spines of the
vertebral column, it will often be found impossible to provide proper
drainage for the abscess from below, and treatment must consist of
caustic solutions carefully injected into all parts of the suppurating
sinuses. A very effective remedy for this purpose consists of 1 ounce of
chlorid of zinc in half a pint of water, injected three times during a
week, after which a weak solution of the same may be occasionally
injected. Injections of Villate's solution or alcoholic solution of
corrosive sublimate, strong carbolic acid, or possibly oil of turpentine
will also prove beneficial. Pressure should be applied from below, and
endeavors made to heal the various pipes from the bottom.

Should the swelling become general, without forming a well-defined
tumor, the placing of 20 to 30 grains of arsenious acid, wrapped in a
single layer of tissue paper, in a shallow incision beneath the skin,
will often produce a sloughing of the affected parts in a week or 10
days, after which the formation of healthy tissue follows. The
surrounding parts of the skin should be protected from any damage from
escaping caustics by the application of lard or oil, as previously
suggested.

Although the successful treatment of fistulas requires time and
patience, the majority of cases are curable. The sinuses must be opened
at their lowest extremity and kept open. Caustic applications must be
thoroughly used once or twice, after which mild astringent antiseptic
washes should be persistently used until a cure is reached.

It sometimes happens that the erosions have burrowed so deeply or in
such a direction that the opening of a drainage passage becomes
impracticable. In other cases the bones may be attacked in some
inaccessible location, or the