How to give a rat an intramuscular injection? - briefly
Restrain the rat, locate the quadriceps femoris muscle, disinfect the area, insert a 27‑30 G needle at a 45° angle, and slowly deliver the prescribed volume. Observe the animal for several minutes for any adverse reaction before returning it to its cage.
How to give a rat an intramuscular injection? - in detail
Administering an intramuscular (IM) injection to a laboratory rat requires precise preparation, proper restraint, accurate site identification, and careful post‑procedure monitoring.
Begin with equipment sterilization. Use a 1‑ml syringe fitted with a 27‑ to 30‑gauge needle, length ½‑to‑¾ inch. Prepare the drug in a sterile vial, verify concentration, and draw the exact volume, eliminating air bubbles by tapping and expelling excess fluid.
Select the injection site. The most reliable muscle is the hind‑limb quadriceps, located midway between the hip and knee on the lateral thigh. The ventral lumbar region (lumbar epaxial muscle) is an alternative for larger volumes. Shave a small area, clean with 70 % ethanol, and allow to air‑dry.
Restrain the rat securely but gently. Place the animal on a padded board, hold the forepaws with one hand, and immobilize the hindlimb with the other hand to expose the target muscle. Avoid excessive force that could cause stress or injury.
Insert the needle at a 90° angle, penetrating the skin and muscle to the full length of the needle. Aspirate gently; if blood appears, withdraw the needle and select a new site. Inject the solution steadily, observing for any resistance. Withdraw the needle swiftly, applying gentle pressure with a sterile gauze pad to minimize bleeding.
After injection, release the rat into a clean recovery cage. Monitor for at least 15 minutes, checking for signs of distress, abnormal gait, or swelling at the injection site. Record the dose, needle size, injection site, and any observations in the animal’s log.
Dispose of used syringes and needles in a puncture‑proof sharps container. Decontaminate work surfaces with appropriate disinfectant. Follow institutional animal care guidelines and biosafety protocols throughout the procedure.