derr's operation for umbilical hernia 359 



prevent complications consist of a thorough washing of the 

 field and perfect sterilization of the skewers. 



TECHNIQUE.— First Step.— Marking the Field.— While 

 the patient is still in the standing position four marks are 

 made around the base of the hernia equally distant from one 

 another. The marks are made by simply snipping off a tuft 

 of hair at each spot. Chalk marks or any certain method of 

 isolating the skin constituting the sac after the patient is 

 placed upon its back, will answer. This marking process is 

 essential because the relation of the skin to the orifice 

 changes as the animal is thrown from the upright to the re- 

 cumbent position, and unless the skin constituting the sac is 

 thus located it will be found that the ligature lies to one side 

 or other of the orifice when the patient is again upon its feet, 

 after the operation is completed. 



Second Step. — Inserting the Skewers. — The patient, hav- 

 ing been cast and secured safely enough to prevent molesta- 

 tion, the space lying within the circle outlined by the four 

 markings is cleansed with antiseptic water, and shaved. The 

 center of the field, which may now occupy a position at the 

 side of the orifice, is then lifted either with the fingers or with 



Fig. 175— Skewer Scheme for Derr's Operation. 



a tumor forceps and drawn up with some force. At the 

 spots previously marked four small incisions (mere punc- 

 tures) to serve as entrances and exits for the skewers, are 

 made with the point of the scalpel. Through these, the sac 

 is transfixed with the skewers so that they cross at right an- 

 gles in the center. 



Third Step. — Ligation of the Sac. — The silk ligature is 

 now passed around the base of the sac beneath the four pro- 

 truding ends of the skewers in the form of a double-half 

 hitch, and drawn as tight as its tensile strength will admit, 

 and after the hitch has been secured by a knot to prevent 

 slipping a number of tight wraps are made with the remain- 

 der of the thread. The protruding ends of the skewers are 

 then shortened with the wire forceps. 



AFTER-CARE. — Little after-care is required. However, 

 the parts should be occasionally examined for possible com- 

 plications. In warm weather the strangulated sac may be- 

 come putrid and even fly-blown unless occasional antiseptic 

 treatment is applied. In such events a wash of formalin solu- 



