Thomson, J., Mungall, W. 2019. Using subcuticular stitching in rats to replace skin closure clips as a refinement. Animal Technology and Welfare 18(1), 75-76.

Skin closure clips are widely used within the University of Edinburgh to close incision sites for various procedures in both rats and mice. In rats the skin closure clips very often come out as a result of cage mates biting each other’s incision sites or for other unknown reasons. One solution is to singly house rats that have undergone surgery. This is not ideal as rats are companion animals and this, therefore, must be approved on a project licence. To overcome the recent problem of rat surgical clips coming out post-surgery we tried using different types and sizes of clips and applicators and re-trained staff in applying the clips, however this did not seem to help. An alternative method of suturing was researched and a short course on subcuticular stitching with Aberdeen knot was provided by one of us using cadavers to practice. YouTube videos were also viewed until competency was confirmed. Thirty rat embryo transfers have been completed with subcuticular stitching finished with the Aberdeen knot. All the incision sites were perfectly closed and infection-free for the duration of the experiment. No adverse effects were noted and rat recipients successfully got pregnant and littered down. Although the time taken to perform the stitching during embryo transfer surgery takes approximately 10-15 minutes longer than to clip, we believe that the benefit outweighs the increased time under anaesthetic. The type of suture recommended for use in embryo transfer and used throughout the University for the subcuticular stitches in rats is Vicryl Rapide™. The use of subcuticular stitching and Aberdeen knots for surgical procedures in rats (i.e. embryo transfer) is a refinement which Edinburgh is rolling out to all users that currently use skin closure clips. For more information regarding this technique please get in touch with Mel Leech (NTCO) and William Mungall (Designated Trainer). An excellent training video can be found at

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