How do you inject antibiotics into a rat? - briefly
Secure the rat in a gentle restraint, shave and disinfect the lower right abdominal region for intraperitoneal injection (or the dorsal scruff for subcutaneous delivery), and load the calculated antibiotic dose into a sterile syringe fitted with a 25–27 G needle. Insert the needle at a 45° angle, confirm placement by aspiration, inject the volume slowly, and withdraw the needle.
How do you inject antibiotics into a rat? - in detail
Administering a therapeutic antimicrobial to a laboratory rat requires strict adherence to aseptic technique, accurate dose calculation, and appropriate injection method.
First, determine the drug’s concentration and calculate the required volume based on the animal’s weight (mg kg⁻¹). Use a calibrated scale to weigh the rat, then apply the formula: dose (mg) = dose rate (mg kg⁻¹) × weight (kg). Convert the dose to a volume using the antibiotic’s stock concentration.
Prepare a sterile work area. Gather the following items:
- 1‑ml syringes with 27‑30 G needles (choose length according to injection site)
- Sterile cotton swabs or gauze
- Antiseptic solution (70 % ethanol or povidone‑iodine)
- Personal protective equipment (gloves, lab coat, eye protection)
- Waste container for sharps
Restrain the rat using a gentle scruff hold or a specialized restrainer to minimize stress while maintaining access to the chosen site. Common routes include:
- Intraperitoneal (IP) – injection into the lower right quadrant of the abdomen, avoiding the bladder and intestines.
- Subcutaneous (SC) – injection into the loose skin over the dorsal neck or flank.
- Intramuscular (IM) – injection into the quadriceps or hind‑limb muscle, using a longer needle to reach muscle tissue.
- Intravenous (IV) – injection into the lateral tail vein, requiring a 30‑31 G needle and careful vein visualization.
For an IP injection, follow these steps:
- Swab the injection site with antiseptic and allow it to dry.
- Insert the needle at a 30‑45° angle, bevel up, penetrating the skin and peritoneum.
- Aspirate gently; absence of blood confirms correct placement.
- Deliver the calculated volume slowly (≤0.5 ml per 100 g body weight) to prevent abdominal distension.
- Withdraw the needle smoothly, apply a brief pressure with sterile gauze, and monitor the rat for normal respiration.
For SC injections, use a shallow angle (10‑15°) and pinch the skin to create a tent before needle insertion. Deliver the volume, then release the skin and observe for any signs of swelling or leakage.
After administration, place the rat in a clean cage with free access to food and water. Record the following data in the animal log: drug name, concentration, dose, route, volume, time of injection, and any immediate reactions. Dispose of needles in a puncture‑proof sharps container and decontaminate surfaces with an appropriate disinfectant.
Regularly inspect the injection site for erythema, edema, or infection. Adjust dosing schedule according to the prescribed regimen and veterinary guidance.