How can a rat be injected? - briefly
A rodent is secured in an appropriate restrainer, the injection site is disinfected, and a sterile syringe with a suitable gauge needle is prepared. The substance is then delivered subcutaneously, intramuscularly, or intravenously according to the experimental protocol.
How can a rat be injected? - in detail
Administering substances to a laboratory rat requires careful preparation, appropriate equipment, and strict adherence to aseptic technique. The process can be divided into three phases: pre‑injection preparation, execution of the injection, and post‑injection monitoring.
Pre‑injection preparation begins with selection of the appropriate route. Common routes include intraperitoneal («IP»), subcutaneous («SC»), intramuscular («IM») and intravenous («IV»). Choice of route depends on the physicochemical properties of the agent, required absorption rate, and experimental objectives. The animal should be weighed to calculate the exact dose, expressed in millilitres per kilogram. Sterile syringes (typically 1 ml or 0.5 ml) and fine‑gauge needles (25‑30 G) are standard. Needles must be inspected for bending or damage before use.
Execution of the injection follows a systematic sequence:
- Restrain the rat gently but firmly, using a tube restrainer or a soft cloth wrap, to minimize stress and movement.
- Verify the needle length matches the intended depth; for «IP» injection, a 25‑G needle of 5‑7 mm suffices, while «IV» access to the lateral tail vein often requires a 27‑G, 13‑mm needle.
- Disinfect the injection site with 70 % isopropyl alcohol, allowing the surface to dry.
- Insert the needle at the correct angle:
- «IP»: bevel up, angled 30‑45° into the lower right quadrant of the abdomen, avoiding the bladder and intestines.
- «SC»: bevel up, shallow insertion at a 10‑15° angle into the dorsal neck or hind‑leg area.
- «IM»: bevel up, perpendicular insertion into the quadriceps or gluteal muscle.
- «IV»: bevel up, shallow insertion into the tail vein, with the tail warmed to dilate the vessel.
- Aspirate gently to confirm absence of blood for non‑vascular routes; presence of blood indicates inadvertent vessel puncture and requires repositioning.
- Deliver the calculated volume steadily, avoiding rapid bolus that may cause tissue damage.
- Withdraw the needle smoothly, apply gentle pressure with sterile gauze to prevent hemorrhage.
Post‑injection monitoring includes observation for immediate adverse reactions such as respiratory distress, excessive bleeding, or abnormal behaviour. Record the injection details—date, time, dose, route, needle gauge, and any complications—in the animal log. Provide appropriate recovery housing, ensuring temperature and humidity remain within recommended ranges.
Safety considerations for personnel involve wearing gloves, lab coat, and eye protection. Dispose of used needles in a puncture‑proof sharps container. Follow institutional animal care and use protocols to guarantee ethical compliance and reproducibility of experimental results.