Which is an appropriate technique for subcutaneous injections in mice?

• A. Lift some skin on the back of the mouse, and insert the needle into the base of the tent.
• B. Inject into the leg muscle
• C. Insert into the tail vein
• D. Pinch the skin tightly and insert near the shoulder blade

Answer: (A)

Subcutaneous injections in mice are delivered into the loose tissue just under the skin. The correct technique is to gently lift a fold of skin on the back to form a tent and insert the needle into the base of that tent so the injection goes into the subcutaneous space. This targets the tissue intended for subcutaneous absorption and avoids deeper tissues or the bloodstream. Injecting into leg muscle would be intramuscular, which is not subcutaneous. Injecting into a tail vein would be intravenous, delivering directly to the bloodstream. Pinching the skin and inserting near the shoulder blade isn’t the standard subcutaneous site, whereas placing the needle at the base of the back-skin tent reliably reaches the subcutaneous tissue.