How do you give an intramuscular injection to a rat? - briefly
Restrain the rat, shave and disinfect the lateral thigh (vastus lateralis), then using a sterile 1‑ml syringe with a 25–30‑gauge needle, insert the needle at a 45° angle into the muscle and inject the calculated volume slowly. Withdraw the needle, apply gentle pressure with sterile gauze, and observe the animal for any adverse reactions.
How do you give an intramuscular injection to a rat? - in detail
Administering an intramuscular injection to a laboratory rat requires preparation, proper equipment, and adherence to aseptic technique. Follow these steps to ensure accurate dosing and minimal distress.
Prepare the injection solution. Verify concentration, calculate the required volume based on the animal’s weight (typically 0.1 mL per 100 g body weight), and draw the fluid into a sterile 1‑mL syringe fitted with a 25‑ to 27‑gauge needle. Remove air bubbles by tapping the syringe and gently expelling any excess.
Select the injection site. The most common location is the dorsal aspect of the hind‑limb, specifically the quadriceps femoris muscle. This area provides sufficient muscle mass and avoids major nerves and blood vessels. Shave a small patch of fur if necessary, then disinfect the skin with 70 % ethanol or an approved antiseptic, allowing it to dry.
Restrain the rat. Use a gentle manual hold or a restraining device that secures the animal without excessive pressure. Position the animal so the selected limb is extended and the muscle is easily accessible.
Insert the needle. Hold the syringe at a 45‑ to 90‑degree angle to the skin, depending on the animal’s size, and advance the needle into the muscle tissue. Confirm proper placement by a slight “pop” sensation as the needle penetrates the fascia. Avoid inserting too deeply, which could reach bone.
Deliver the dose. Depress the plunger steadily to inject the calculated volume. Observe for resistance; if encountered, withdraw slightly and readjust the needle angle. After delivery, withdraw the needle promptly and apply gentle pressure to the site with a sterile gauze pad to minimize bleeding.
Dispose of used materials. Place the needle and syringe in a designated sharps container, and clean the work area with appropriate disinfectants. Record the administered dose, site, and any observations in the animal’s log.
Monitor the rat post‑injection. Observe for signs of distress, swelling, or abnormal behavior for at least 30 minutes. Provide warmth and return the animal to its cage once fully recovered.