Fitzwater, A., Zhang, L. 2024. A cost-effective restraint method for safer subcutaneous scruff injections and reducing stress in mice and handlers. Laboratory Animal Science Professional 12(1) (January/February), 52-53.

Subcutaneous injection is a vital technique in mouse-based biomedical research. Compared to other injections, the subcutaneous method poses fewer technical challenges and reduces acute toxicity risks due to slower absorption. Several suitable subcutaneous injection sites exist in mice, including the scruff/neck, flank, abdomen, and chest. The scruff provides the most convenient site for easy access to loose skin for tenting and injections. However, this site allows mice to see the incoming needle and potentially bite or scratch. Resulting movements increase stress in both the mouse and handler. To resolve these issues, we have developed a method for safe, effective scruff injections that mitigate associated risks to mouse and handler. These devices use routine labware or plastic bottles, so the cost is minimal. The key is to block the vision of the mouse using a simple restraint. In summary, we describe the use of a simple device for safe and effective subcutaneous injections of mice and possibly other rodents, which can reduce stress for both animals and handlers.