What are key considerations when performing subcutaneous injections in mice?

• A. It must be intramuscular to be effective.
• B. Ensure the injection is subcutaneous, use appropriate volume, and choose an injection site with minimal discomfort.
• C. Use the maximum possible volume regardless of site.
• D. Subcutaneous injections are not advised in mice.

Answer: (B)

When giving injections in mice, the goal is to deliver the fluid into the subcutaneous space while keeping the dose small and choosing a site that minimizes discomfort. Subcutaneous administration places the fluid under the skin where absorption is slower and more uniform, and it’s generally easier and less traumatic for mice than injections into muscle or other tissues. The best approach is to ensure the injection stays in the subcutaneous tissue, use a small, appropriate volume for a mouse, and select a site that is least stressful and least likely to cause tissue damage—often the dorsal scruff or a loose-skinned area along the back.

Keep volumes tiny and avoid sites that are tight or near joints or underlying muscle. Use sterile technique, a suitable needle size, and a gentle technique (tent the skin, insert shallowly, and inject slowly) to minimize discomfort and tissue injury. This combination—correct route, careful volume, and a comfortable site—supports reliable absorption and animal welfare.

Choices suggesting it must be intramuscular, or using the maximum possible volume, or avoiding subcutaneous injections altogether, don’t fit because they ignore the purpose and mechanics of the subcutaneous route and can increase discomfort or harm.