Fistula in Ano signifies an ulcer through the rectum, and a passage by the side of it down through the fibres of the sphincter ani, the muscle which surrounds the anus closing it by contraction.

Fistula of the anus may be met with in dogs, more commonly among the house pet overfed and deprived of needed exercise. This affection is a common result of abscess near the rectum. One eminent surgeon maintains " that it always commences with an ulceration of the mucous membranes of the rectum, and an escape of the fecal matter into the cellular tissue, which gives rise to abscess and fistula".

This affection may exist as follows - complete, having an external opening near the anus, and another into the bowel above the sphincter muscle - as a blind external fistula which has no opening into the bowel - as the blind intestinal fistula which opens into the bowel but not externally.

Symptoms

Irritation and pain in the affected part causes the animal to act much the same as when suffering from piles, licking the anus and dragging himself along the floor, etc. If the fistula opens externally, less difficulty will be experienced in making a diagnosis; still in but few cases will detection be easy, but rather the reverse, as in many instances the opening will be minute and need close scrutiny to discover it. The course of an external fistula is that of a frequent recurring abscess; the cavity fills up and discharges, the opening then closes and again the cavity fills. In searching for a fistulous opening, a minute drop of matter in the centre of a slight swelling will often mark its location. To explore its track a small steel knitting needle will be sufficient.

When a blind internal fistula exists its presence may be suspected by a discharge, bloody, watery in character, and at times offensive.

Treatment

The constitutional treatment may be left to owners and care-takers but the local surgical treatment never. The constitutional treatment is symptomatic; correct abuses, regulate the diet, and if weak, strengthen. Constipation should be overcome by judicious dieting; among other articles of food no better laxative is known than liver, which can be fed in sufficient quantity to keep the bowels regular, or if preferred the cream of tartar and sulphur as advised in piles may be given instead.

Exercise should be enforced. If tonic remedies are demanded, cod-liver oil, iron, or quinine may be administered.

A radical cure of fistula demands a surgical operation. Of several popular methods, the elastic ligature is advised. When an operation is imperative, a competent surgeon should be employed and the method of procedure left entirely to his judgment.