Rowel, in farriery, signifies a kind of issue, artificially formed in horses, with a view to drain super-duous humours.

Rowels are introduced into the abdomen, the inside of the thighs, the breast, and outside of the shoulders and hips of a horse. The operation is performed by an incision through the skin, about 3-8ths of an inch in length, then separating it from the flesh with the finger, or passing an ivory folder around the orifice: next, a thin piece of leather, of a circular shape, about the size of a silver crown piece, should be provided, and a large round hole made in its centre. Before the leather is introduced between the skin and muscles, it must be partially covered with lint or tow, and immersed in some digestive ointment: a pledget of tow is likewise dipped in a similar unguent, and carefully put into the orifice, so as completely to exclude atmospheric air. The parts around it soon swell ; a copious discharge of yellow serum or water follows ; and, in two or three days, at the farthest, the matter will appear thick, gross, and white, when the rowel is said to suppurate.

Although these issues are doubtless of great service in some cases, yet, like many other operations injudiciously practised on horses, they sometimes injure their constitution; and, instead of suppurating, become gangrenous.

Rowels are eminently useful in carrying off rheums or defluxions from the eyes ; in great swellings of the glands, about the throat and jaws, which sometimes threaten suffocation. In the vertigo or staggers, apoplexy, and in large tumors arising suddenly on the legs, heels, etc. when attended with a discharge of thin ichorous matter; as well as in a variety of other disorders, the application of this remedy should be determined by the Veterinary Surgeon.—See SETONS.