How can you give a rat an intramuscular injection? - briefly
Restrain the rat, locate the lateral thigh muscle (vastus lateralis), disinfect the area, insert a 25‑27 G needle at a 45° angle, aspirate, deliver the prescribed volume, and withdraw the needle. Use a calibrated syringe and monitor the animal for any adverse response.
How can you give a rat an intramuscular injection? - in detail
Administering a muscle injection to a laboratory rat requires strict aseptic technique, precise anatomical knowledge, and careful handling to minimize stress and injury.
First, gather all materials: sterile syringe (0.5–1 mL capacity), appropriate gauge needle (25–27 G, 5–13 mm length depending on rat size), the prepared drug solution, antiseptic swabs, disposable gloves, and a soft restraint device or a calibrated restraining tube. Verify the dosage, volume, and concentration against the animal’s weight and the experimental protocol.
Second, immobilize the animal. Place the rat in a restraining tube with the head slightly elevated, or use a manual hold with the thumb and forefinger securing the scruff while the other hand supports the torso. Ensure the rat is calm; excessive struggling can compromise needle placement.
Third, locate the injection site. The preferred muscle is the quadriceps femoris on the hind limb, approximately midway between the hip and knee joints, lateral to the femur. Disinfect the area with a 70 % isopropanol swab and allow it to dry.
Fourth, perform the injection:
- Attach the sterile needle to the syringe, expel any air bubbles, and draw the exact volume of solution.
- Hold the needle at a 45‑degree angle to the skin, bevel up.
- Insert the needle through the skin and into the muscle tissue to the full length of the needle, ensuring penetration beyond the subcutaneous layer.
- Depress the plunger steadily to deliver the drug.
- Withdraw the needle swiftly, applying gentle pressure to the puncture site with a sterile gauze pad to control bleeding.
Finally, monitor the rat for several minutes after the procedure. Return the animal to its home cage, observe for signs of distress, pain, or injection site swelling, and record the details of the administration (date, time, dose, site, needle size) in the laboratory log. Proper documentation and post‑procedure observation are essential for reproducibility and animal welfare compliance.