How to give injections in a rat's leg? - briefly
Restrain the rat, expose the lateral thigh, clean the site with antiseptic, and select a 27‑30 G needle appropriate for the volume. Insert the needle at a 45° angle into the gastrocnemius muscle, deliver the dose steadily, withdraw, and apply gentle pressure to prevent bleeding.
How to give injections in a rat's leg? - in detail
Administering an intramuscular dose into a rat’s hind limb requires precise preparation, proper restraint, and adherence to aseptic technique.
First, gather all necessary supplies: sterile syringes (typically 1‑ml), appropriate gauge needles (27‑30 G), the drug prepared in a sterile vial, alcohol swabs, disposable gloves, a clean work surface, and a warming pad if the animal is cold‑blunted. Verify the dose, calculate volume, and label the syringe clearly.
Second, acclimate the animal to the procedure area for at least five minutes. Apply gloves and disinfect the injection site—usually the vastus lateralis muscle on the lateral thigh—by swabbing with 70 % ethanol and allowing it to dry.
Third, restrain the rat using a gentle but firm method to prevent movement without causing stress. Common techniques include:
- Holding the animal in a supine position with the hind limbs extended, supporting the torso with one hand while the other secures the target leg.
- Using a soft restraining tube or a plexiglass holder that limits limb motion while keeping the animal conscious.
Fourth, insert the needle at a 45‑degree angle to the skin surface, directing it toward the muscle belly. Advance the needle until the hub contacts the muscle, ensuring the tip is fully within the tissue. Aspirate gently to confirm absence of blood; if blood appears, withdraw and reposition.
Fifth, deliver the calculated volume slowly (approximately 0.1 ml per 100 g body weight) to avoid tissue rupture. After injection, withdraw the needle at the same angle, apply gentle pressure with a sterile gauze pad to minimize bleeding, and observe the site for any immediate reaction.
Finally, monitor the rat for at least ten minutes post‑procedure. Look for signs of distress, abnormal gait, or swelling at the injection site. Record the administered dose, time, and any observations in the animal’s log. Dispose of all sharps in a designated container and clean the work area with an appropriate disinfectant.
Following these steps ensures accurate drug delivery, minimizes animal discomfort, and complies with institutional animal care guidelines.