Where should I inject a rat? - briefly
Inject the substance into the intraperitoneal cavity for rapid systemic distribution, or use the subcutaneous space for slower absorption; the choice depends on the experimental aim. The intraperitoneal route is generally preferred for most pharmacological studies.
Where should I inject a rat? - in detail
Injecting a laboratory rat requires precise placement to ensure reliable absorption and minimize tissue damage. The most common sites are:
- Intraperitoneal (IP) cavity – entry through the lower right quadrant of the abdomen, avoiding the liver and bladder. Use a 25‑27 G needle, insert at a shallow angle, and aspirate before injection to confirm placement.
- Subcutaneous (SC) tissue – injection into the loose skin over the dorsal neck or flank. Hold the skin taut, insert the needle at a 45° angle, and release the dose slowly.
- Intramuscular (IM) muscle – target the hind‑limb quadriceps or the gluteal muscle. Position the rat in a supine or lateral stance, locate the muscle bulk, and insert the needle perpendicularly to a depth of 5–7 mm.
- Intravenous (IV) route – access the lateral tail vein. Warm the tail to dilate the vessel, insert a 30‑32 G catheter at a shallow angle, and flush with sterile saline before delivering the compound.
Key procedural steps:
- Restrain the animal using a calibrated restrainer or manual grip to prevent movement.
- Disinfect the injection site with 70 % isopropanol; allow alcohol to evaporate.
- Verify needle gauge matches the volume and viscosity of the solution.
- Perform a gentle aspiration to confirm non‑vascular placement for IP and SC injections.
- Deliver the dose steadily; avoid rapid bolus that can cause reflux or tissue rupture.
- Observe the rat for 2–5 minutes post‑injection, monitoring for signs of distress, hemorrhage, or improper administration.
Documentation should include the exact site, needle size, volume administered, and any observed adverse reactions. Consistent technique across experiments reduces variability and enhances reproducibility.