How to give an intramuscular injection to a rat? - briefly
Use a sterile syringe with the correct dose, locate the quadriceps femoris muscle, disinfect the site, and insert the needle perpendicular to the skin. Inject the solution slowly, withdraw the needle, and apply gentle pressure to the injection site.
How to give an intramuscular injection to a rat? - in detail
Administering an intramuscular injection to a laboratory rat requires strict adherence to aseptic technique, appropriate equipment, and accurate dosing. The procedure can be divided into preparation, injection, and post‑injection phases.
The preparation phase includes the following steps:
- Verify the animal’s identification and health status; ensure the rat is acclimated and not exhibiting signs of distress.
- Calculate the required volume based on the drug concentration and the animal’s weight (generally 0.1 ml per 100 g body weight for most substances).
- Gather sterile supplies: 1 ml syringe, 26‑27 G needle, antiseptic swabs, sterile gauze, cotton‑tipped applicator, and a sharps container.
- Prepare the injection solution under a laminar flow hood or clean bench; draw the exact volume into the syringe, expel air bubbles, and label the syringe with drug name, concentration, and dosage.
- Warm the rat gently (e.g., by placing it on a heating pad for a few minutes) to promote vasodilation and reduce muscle tension.
During the injection phase:
- Restrain the rat securely but gently, using a towel or a specialized restrainer to expose the hind limb while minimizing stress.
- Identify the appropriate injection site: the lateral aspect of the quadriceps femoris muscle, midway between the hip and knee, avoiding major blood vessels and nerves.
- Disinfect the skin with an alcohol swab, allowing it to air‑dry.
- Hold the syringe like a pencil, insert the needle at a 45‑degree angle to the skin surface, penetrating the muscle tissue to a depth of approximately 5‑7 mm for adult rats.
- Aspirate briefly to confirm the needle is not within a blood vessel; the absence of blood indicates proper placement.
- Depress the plunger steadily, delivering the entire volume in a single motion.
- Withdraw the needle swiftly, applying gentle pressure with sterile gauze to the injection site for 10–15 seconds to prevent bleeding.
The post‑injection phase comprises:
- Observe the rat for at least 5 minutes for immediate adverse reactions such as excessive bleeding, abnormal respiration, or signs of pain.
- Return the animal to its home cage, providing easy access to food, water, and bedding.
- Record the procedure details in the animal log, including date, time, drug administered, dose, injection site, and any observations.
- Dispose of the needle and syringe in a designated sharps container; decontaminate reusable equipment according to institutional biosafety protocols.
Adherence to these steps ensures accurate drug delivery, minimizes tissue trauma, and upholds ethical standards for animal research.