How to correctly give injections to rats? - briefly
Use a sterile 27–30 G needle, gently restrain the rat with a scruff hold, disinfect the chosen site (e.g., subcutaneous over the dorsal neck or intraperitoneal in the lower right quadrant), and inject the dose steadily; observe the animal briefly after administration.
How to correctly give injections to rats? - in detail
Administering injections to laboratory rats requires strict adherence to aseptic technique, accurate dose calculation, and appropriate restraint. Begin by confirming the animal’s identification, weight, and health status. Use a calibrated scale to determine the exact dose, then dilute the substance to a volume that does not exceed 0.1 mL per 10 g of body weight for subcutaneous and intraperitoneal routes, and 0.05 mL per 10 g for intramuscular injections.
Prepare equipment in a clean workspace. Select a sterile needle and syringe based on injection site: 25‑27 G, ½‑inch needles for subcutaneous injections; 23‑25 G, ¾‑inch needles for intraperitoneal delivery; 27‑30 G, ½‑inch needles for intramuscular administration in the hindlimb. Attach the syringe, expel air bubbles, and draw the calculated volume.
Restraint methods vary with injection type. For subcutaneous or intraperitoneal injections, use a gentle scruff hold: grasp the skin behind the neck with thumb and forefinger, allowing the rat to lie on its back. For intramuscular injections, position the animal in a supine posture, extend the hindlimb, and support the thigh with a second hand. Ensure the animal remains immobile without excessive force; excessive pressure can cause injury or stress.
Injection sites:
- Subcutaneous: fold of skin over the dorsal cervical region or lateral flank; insert needle at a 45° angle, withdraw slightly, and inject slowly.
- Intraperitoneal: lower right quadrant of the abdomen; insert needle at a 30° angle, avoid puncturing organs, and deliver the dose steadily.
- Intramuscular: cranial portion of the quadriceps femoris; insert needle perpendicular to the muscle surface, ensure full penetration, and administer the solution.
- Intravenous (tail vein): warm the tail with a heat lamp, locate the lateral vein, insert a 30‑31 G needle bevel up at a shallow angle, and inject the solution quickly.
After injection, withdraw the needle smoothly, apply gentle pressure with a sterile gauze to prevent bleeding, and release the animal back into its cage. Observe the rat for at least five minutes for signs of distress, hemorrhage, or adverse reactions. Record the following details in the animal’s log: date, time, investigator, drug name, concentration, administered volume, injection route, needle size, and any observed complications.
Maintain a clean environment by disinfecting work surfaces, disposing of sharps in approved containers, and sterilizing reusable equipment. Follow institutional animal care protocols and relevant regulatory guidelines to ensure ethical and reproducible results.