How are antibiotic injections given to a rat? - briefly
A sterile syringe with a fine‑gauge needle delivers the antibiotic subcutaneously or intraperitoneally while the rat is gently restrained, using a dose calculated per body weight.
How are antibiotic injections given to a rat? - in detail
Administering antibiotics to a rat requires strict adherence to aseptic technique, accurate dosing, and appropriate injection site selection. The procedure begins with preparation of the drug solution. Dilute the antibiotic to the prescribed concentration using sterile saline or an approved carrier, and filter the mixture through a 0.22‑µm membrane if sterility is uncertain. Record the calculated dose in milligrams per kilogram of body weight, then convert to the exact volume for the individual animal, keeping the total injected volume below 0.1 mL per 10 g of body mass to avoid tissue distension.
Select the injection route based on the drug’s pharmacokinetics and the experimental design. Common routes for rodents include:
- Intraperitoneal (IP): Insert a 25‑30 G needle at a 30‑45° angle into the lower right quadrant of the abdomen, avoiding the midline and major organs. Aspirate gently to confirm entry into the peritoneal cavity before delivering the dose.
- Subcutaneous (SC): Lift a small fold of dorsal skin, insert a 27‑30 G needle bevel up at a shallow angle, and deposit the fluid into the loose subcutaneous tissue. This route is suitable for slow‑release formulations.
- Intramuscular (IM): Target the quadriceps femoris or the hind‑limb gluteal muscle. Use a 25‑27 G needle, insert perpendicularly to a depth of 2–3 mm, and inject the volume slowly to reduce tissue trauma.
- Intravenous (IV): For rapid systemic effect, cannulate the lateral tail vein with a 30‑31 G catheter. Secure the catheter, confirm blood return, then administer the antibiotic over 10–15 seconds.
Restraint must minimize stress and injury. Employ a calibrated rodent restrainer or use a gentle hand‑hold technique: place the rat on a padded surface, secure the forepaws, and support the body with the opposite hand. For repeated dosing, consider brief isoflurane anesthesia (1–2 % in oxygen) to facilitate precise needle placement while maintaining physiological stability.
After injection, observe the rat for at least five minutes. Check the injection site for bleeding, swelling, or discoloration. Record the administration details—date, time, drug, dose, route, needle gauge, and any adverse reactions—in the laboratory log. Dispose of needles in a certified sharps container and decontaminate work surfaces with an appropriate disinfectant.