How can I administer a subcutaneous injection to a rat? - briefly
Restrain the rat, lift the dorsal flank skin to create a tent, insert a 25–30 G needle at a shallow angle into the subcutaneous space, and slowly deliver the required volume.
How can I administer a subcutaneous injection to a rat? - in detail
To perform a subcutaneous injection in a laboratory rat, follow a systematic protocol that addresses preparation, technique, and post‑procedure care.
Equipment and materials
- Sterile hypodermic needle (25‑27 G, ½‑inch length) and appropriate syringe
- Injection solution, prepared under aseptic conditions
- Alcohol swabs or 70 % isopropyl‑alcohol pads
- Disposable gloves, lab coat, and eye protection
- Sharps container for needle disposal
- Restraint device (e.g., tube or custom cradle)
Pre‑injection preparation
- Verify the animal’s identification and ensure it is healthy.
- Warm the injection solution to room temperature; cold fluid can cause discomfort and vasoconstriction.
- Load the syringe, expel air bubbles, and confirm the correct dose.
- Clean the injection site—typically the loose skin over the dorsal lumbar region—with an alcohol pad and allow it to dry.
Restraint and positioning
- Place the rat in a restraint tube or gently hold it with one hand supporting the head and the other securing the torso.
- Extend the skin over the chosen site by pinching a fold between thumb and forefinger, creating a tent that isolates the subcutaneous space.
Injection technique
- Insert the needle at a 45‑degree angle to the skin surface, advancing until the bevel is fully embedded in the tented tissue.
- Aspirate briefly to ensure no blood is drawn, confirming placement outside the vasculature.
- Depress the plunger steadily to deliver the entire volume.
- Withdraw the needle swiftly, maintaining the skin tent to minimize leakage.
Post‑injection care
- Release the animal into a clean cage and observe for at least five minutes for signs of distress, bleeding, or abnormal behavior.
- Apply gentle pressure to the site if any fluid leakage occurs.
- Record the procedure details (dose, volume, site, time) in the animal log.
- Dispose of the needle in a designated sharps container and decontaminate any reusable equipment.
Adhering to these steps ensures accurate delivery of the compound, reduces the risk of tissue trauma, and complies with standard laboratory animal welfare guidelines.