How can I give an injection to a rat's paw? - briefly
Secure the rat, clean the dorsal surface of the paw, and inject the required volume subcutaneously using a 30‑gauge needle at a shallow angle. Dispose of the needle properly and observe the animal for any adverse effects.
How can I give an injection to a rat's paw? - in detail
Administering a medication into a rat’s paw requires strict aseptic technique, precise handling, and appropriate equipment.
First, gather supplies: sterile 27‑30 G needle, syringe calibrated for the intended volume (typically 0.1–0.2 ml), antiseptic swabs (70 % ethanol or povidone‑iodine), a heat‑laminated restraining platform or a small transparent tube, and a source of mild anesthesia (isoflurane or a short‑acting injectable such as ketamine‑xylazine). Prepare a clean work surface and wear gloves.
Second, anesthetize the animal. Place the rat in an induction chamber with 2–3 % isoflurane until loss of righting reflex, then maintain with a nose cone at 1–1.5 % isoflurane. Verify depth of anesthesia by checking pedal reflex.
Third, secure the rat. Transfer the anesthetized animal onto the restraining platform, positioning the paw to be injected so that the dorsal surface is exposed and the animal cannot withdraw the limb. Use a small piece of gauze to gently stabilize the foot without applying pressure to the injection site.
Fourth, identify the injection site. For intramuscular delivery, locate the extensor digitorum longus muscle on the dorsal paw, approximately 2 mm distal to the metatarsal joint. For subcutaneous administration, choose a loose skin area on the lateral aspect of the paw, avoiding visible vessels.
Fifth, disinfect the area. Apply a sterile swab soaked in antiseptic, let it dry, then repeat with a second swab to ensure a clean surface.
Sixth, perform the injection. Hold the syringe like a pen, insert the needle at a 45‑to‑90° angle depending on tissue depth (steeper for intramuscular, shallower for subcutaneous). Advance the needle fully into the target tissue, aspirate gently to confirm no blood return, then deliver the calculated volume at a steady pace. Withdraw the needle swiftly and apply gentle pressure with a sterile gauze to minimize bleeding.
Seventh, monitor recovery. Keep the rat under observation until normal locomotion resumes, typically 5–10 minutes. Return the animal to its cage, provide a warm environment, and record the procedure details (drug, dose, volume, site, needle gauge).
Key points to avoid complications:
- Use the smallest gauge that accommodates the drug volume.
- Do not exceed 0.2 ml per injection to prevent tissue distension.
- Maintain sterility throughout to prevent infection.
- Verify needle placement before injection to avoid intravascular delivery.
By following these steps, the injection can be administered safely and reproducibly.