How can I give a rat an intramuscular injection? - briefly
Use a sterile 25‑30 G needle to inject the calculated dose into the rat’s quadriceps muscle, inserting the needle at a 45° angle while the animal is gently restrained, then withdraw the needle and apply gentle pressure to the site. Observe the rat for any adverse reaction before returning it to its cage.
How can I give a rat an intramuscular injection? - in detail
Administering an intramuscular injection to a laboratory rat requires precise preparation, proper restraint, and careful technique to ensure accurate dosing and minimize trauma.
Begin by gathering sterile equipment: a 1‑ml syringe, a 25‑27‑gauge needle (0.5–0.7 mm length for adult rats), the intended drug, antiseptic swabs, and a clean work surface. Verify the correct dose, dilute if necessary, and draw the solution into the syringe, eliminating air bubbles by tapping the barrel and gently expelling excess fluid.
Select the injection site. The most reliable locations are the lateral thigh (quadriceps) or the dorsal lumbar region. For the thigh, identify the midpoint between the hip and knee, then move laterally to the muscle bulk. For the lumbar area, locate the space between the last rib and the pelvis, avoiding the spinal column.
Restrain the animal using a firm but gentle method. A common approach is to hold the rat in a scruff‑hold, supporting the body with the other hand, or to place it in a transparent restrainer that allows visual monitoring while limiting movement. Ensure the animal is calm; excessive stress can alter physiological responses.
Disinfect the chosen site with an alcohol swab, allowing it to dry. Insert the needle at a 90‑degree angle, advancing until the hub contacts bone or the full length of the needle is inserted, depending on muscle depth. Aspirate gently to confirm absence of blood; a positive aspiration indicates vascular entry and requires repositioning.
Inject the calculated volume slowly, typically not exceeding 0.1 ml per gram of body weight to prevent tissue rupture. After delivery, withdraw the needle steadily, apply gentle pressure with a sterile gauze pad to reduce bleeding, and monitor the injection area for swelling or discoloration.
Post‑procedure care includes returning the rat to its cage, observing for signs of distress, pain, or adverse reactions for at least 30 minutes, and recording the injection details (date, time, dose, site, needle size). Dispose of sharps in a designated container and clean the work area with appropriate disinfectants.
Adhering to these steps ensures accurate intramuscular delivery, promotes animal welfare, and maintains experimental integrity.