FISTULAE.
—A chronic discharge from some tubelike channel, with no tendency to heal. Fistulæ are most common in horses. They may be located on the withers (fistulous withers), on the side of the face (tooth fistulæ), on the breast bone (sternal fistulæ), or on the lower jaw (salivary fistulæ). Fistulous withers are caused from some external injury (the animal rolling on a rock, ill-fitting collars, the saddle pressing on the withers, or from being struck by a club). Tooth fistulæ are caused by a decayed tooth. The pus in trying to get out of the body takes the easiest course and eats through the bones of the face and escapes, causing a chronic discharge. A sternal or breast fistula is caused by some sharp object being run into the breast and striking the breast bone, injuring it and causing decay and pus formation. A salivary fistula is caused by an injury to the tube which carries the saliva from the gland to the mouth.
Symptoms of Fistulous Withers.
—At first a large swelling appears on one or both sides of the withers. In about a week this enlargement becomes soft, and the fluid contained in it can be distinctly felt. If left to itself the swelling gets larger and softer, and in a month or so breaks and discharges the contents. The fluid that comes from the swelling is first thin and streaked with blood; later it contains yellow-appearing masses. The last material is the pus. The sack that formed at the time the fistula was caused is a hard, firm membrane. This keeps the wound from healing. For this reason the discharge becomes chronic. The wound may heal and there will be no pus discharged for a month, then the old opening will be broken and the pus will flow out again until the sack is emptied. This healing of the wound and then breaking again may be kept up for years, unless the disease is properly treated. As a general rule, the affected animal runs down in flesh.
FISTULOUS WITHERS
Sometimes only the skin and tissue immediately under it become affected. In such cases little trouble need be anticipated; but if the cause is not removed, the deeper structures, muscles and bones, may become diseased.
Treatment for fistulous withers consists of opening the swelling and inserting muslin strips that have been dipped into terchloride of antimony. Insert one and remove, inserting another and leave in the opening for three or four hours. Repeat this operation every four or five days for a month. In addition rub on the outside of the swelling once every two weeks a mixture made of 2 teaspoonfuls of cantharides and 4 tablespoonfuls of lard. The tooth fistula usually calls for the removal of the tooth and thorough disinfection of the opening from the face through to the mouth. With a sternal fistula the diseased bone may need to be scraped and then antiseptic washes used daily. The salivary fistula is more difficult to treat. Better have the veterinarian to examine, and an operation may be necessary.