198 OPERATIONS ON THE SKIN AND CELLULAR TISSUE. 



to allow the introduction of the rowel, rolled or doubled on itself ; 

 then, with the scissors passed flatwise under the skin, a pouch is 

 made, by dividing the cellular tissues, of sufficient dimensions to 

 secure the rowel, which is to be opened or unrolled and flattened 

 in the pouch in such a manner as to bring its central opening in 

 correspondence with the incision in the skin. 



This form of seton can remain for a period of from fifteen to 

 twenty days, and there are cases where it has been kept in place 

 as long as six weeks. It can easily be removed with the forceps 

 or a pointed tenaculum. 



Trochiscus. 



This is an exutory formed of some mineral or vegetable sub- 

 stance, sometimes termed an issue pea, possessed of irritating or 

 even caustic properties, which are introduced under the skin in the 

 same manner as the rowel. They differ from the other exutories 

 by causing a greater amount of irritation, a higher degree of in- 

 flammation, and for that reason are left in place for a shorter 

 period, and are removed as soon as inflammatory symptoms are 

 well estabhshed. They are less frequently used in solij)eds, but 

 are of more common employment in cattle. In the former, how- 

 ever, lameness of long standing in the upper segments of the legs 

 has been successfully relieved by them. In cattle they are often 

 inserted in the dewlap. They can be introduced directly under 

 the skin, either through an incision made alone, or attached to a 

 seton, which may continue longer in place after the removal of the 

 trochiscus. 



Accidents, Sequels of Setons. 



The accidents which sometimes follow the application of setons 

 are: hemorrhage, gangrenous swellings, abscesses, excessive 

 granulations or fungosities, and indurations. 



(a) Hemorrhage. — In ordinary circumstances, their introduc- 

 tion is accompanied by the escape of only a few drops of blood, 

 but there are cases where abundant hemorrhages occur, either 

 resulting from an injury to some blood vessels, or because of a 

 special hemorrhagic predisposition ia the animal, as when it is in 

 a debilitated or anaemic state. 



When there is hemorrhage, it usually shows itself at the con- 

 clusion of the operation, the blood oozing in drops from the open- 



