84 



VETERINARY SURGICAL OPERATIONS 



gradually cuts- its way through by pressure upon the incar- 

 cerated tissues. (Fig. 39.) 



EQUIPMENT. — 1. Full curved special needles, aneur- 

 ism needles, and straight needles are sometimes needed to 

 effectually carry ligatures into desired positions. (Figs. 40-41.) 



2. Cords of silk or linen thread, the size of which must 

 vary according to the requirement, are the best ligature ma- 

 terial. Exceptionally large s.trands are needed in ligating 

 large growths, and in every case they must be strong enough 

 to withstand the severe traction necessary to tighten them 

 enough to strangulate the growth. For ligating ves- 

 sels the ligatures must vary according to the size of the ves- 

 sels, not on account of strength but because small threads 

 applied to large vessels will cut them off too rapidly — before 

 the coagulum has effectually occluded the lumen of the 

 stump. 



Fig. 40. 



Fig. 41. 

 Pigs. 40 and 41 — Aneurism Hool£ and Needle used in Ligation. 



3. Common rubber bands of various sizes are utilized for 

 elastic ligatures. 



TECHNIQUE.— The Ligation of Blood Vessels.-A 



blood vessel to be effectually ligated must be isolated and 

 drawn out of the tissues with a forcep, so that the ligature 

 when tied will not slip from the stump. When surrounding 

 tissues are caught in a ligature it is very liable to slip off as 

 soon as the parts are disturbed by movements or manipula- 

 tions, but this accident can be prevented when the vessel can 

 not be isolated and drawn out, -by encircling the spot with a 

 tobacco-pouch stitch, which, when drawn taut, will retain its 

 position against any ordinary disturbance. The insertion of 

 such stitches is facilitated by a double special needle arranged 

 in the form of a forcep. (Fig. 42.) The needles are pushed 

 through the tissues on either side of the bleeding spot, 

 threaded, drawn back, and then unthreaded, thus leaving 

 the vessel surrounded with a ligature ready to be tied.. 



