As this term is frequently used by practitioners, it may be well to explain that it is a Greek word signifying a removal from one place to another, employed as a technical designation in describing a change of the seat of disease from one part of the animal structure to another, which is by no means uncommon: for instance, when the feet are attacked with fever, that malady will appear to remove itself to some other and probably distant part, and fix itself on the lungs or other viscera, the same way that inflammation of the lungs and other parts of the upper structure will change amongst themselves, or from their own seat of disease to the feet.[34] I have even known superpurgation (occasioned, in a pair of horses, by _undue_, but not severe work when under the irritation of the medicine) to cause fever of the feet, by a metastasis, changing the seat of irritation from the internals to the extremities—a very palpable case in point.
The insertion of a seton properly belongs to the professional man, and only for the guidance of persons who, from living in remote neighbourhoods or other causes, cannot possibly procure the assistance of such, the following information is inserted, in order to obviate the necessity for some ignorant farrier being permitted to perform the operation after his own fashion. The skin is first divided, by surgical scissors made for such purposes, to the width of the seton-needle to be used, which must be wide or narrow, according to the orifice required, with white linen tape passed through its eye, about the same width as the needle and orifice. The needle is then inserted at the opening, and, passing superficially under the skin, is directed towards the point where the lower or depending orifice is intended to be, and where the needle and tape are drawn out. Sufficient tape must be left at each extremity to admit not only of its being tied round small rolls of tow which keep the tape from running through at either side, but some inches of the tape should be left in addition at one end, to allow of a portion being drawn out at one orifice each day, and a fresh piece with dressing being drawn in at the other.
In cases where there is already an upper orifice with sinuses, the surgeon (if he does not lay the place entirely open with a knife, which, if the sinuses are deep-seated, he will do) will insert the seton-needle at such orifice, no incision with the scissors being necessary, the direction of the sinuses having been first ascertained by the careful use of the probe. The dressing to be applied to the tape will be either chloride of zinc lotion, Venice turpentine, or tincture of arnica lotion (_see_ “Lotions”), according as the healing or discharging process may be desired, the first being the healing application. Farriers attempting this operation will even now adopt an old and most objectionable practice of tying the two ends of the seton-tape together, and turning it round at each fresh dressing; the consequence being that, if anything happen to catch in the loop thus made, the whole piece of skin may be dragged out.