When ligating a vessel in preparation for transection, it is ideal to place a clamp on the side that will be removed to save you the time of tying a ligature that will ultimately end up in the trash.
However, sometimes it is inconvenient or unwise to have many hemostatic clamps in your field. For instance if you have a very friable mass like a large neoplasm or a very distended pyometra, the handles of your many clamps might interfere with precise surgical technique or could even result in rupture of the mass. In those situations you may find you are tying many ligatures and it can be easy to lose track of what is staying with the pet and what is leaving with the mass.
To make identification easy, I leave one arm of the ligatures that will be removed from the pet quite long (1.5-2 cm, solid arrow). When I go back to transect vessels, all of the long tags are on the side that leaves with the mass and they are easy to find. While this goes against strict suture conservation, we are not talking about wasting loads of suture here, just leaving the short end of your normal knot long, rather than trimming it to 2mm.
While we are on the subject of suture conservation, let me add my humble opinion. The most vital part of suturing in ANY patient is NOT how little suture you use. The most critical aspects of suturing are precision of every bite, exacting attention to tension and knot tying, and of course delicacy of your tissue handling during suturing while eliminating dead space and minimizing tension that precipitates wound separation. Yes, inexperienced surgeons tend to “waste” more suture than experienced surgeons. Yes, suture is a tangible cost in the surgical suite. However, trying to place a beautiful subcuticular pattern and tie a perfect knot when you are down to the last few centimeters of your suture is not only foolish, it is consciously putting your patient at unnecessary risk. Suture getting short? Ask for more suture.
Technician or boss or anyone giving you static about “wasting” suture? Tell him or her that you are actively improving your technique and that you do not want to risk knot failure or inadequate closure simply to avoid opening another packet of suture. Average package of sterile gauze: $2.35. Average packet of absorbable suture: $4.17. Average packet of non-absorbable suture: $2.75. Knowing your knots won’t unravel and your closure was performed to the best of your abilities: PRICELESS.