How do you anesthetize a rat? - briefly
Commonly, rats are anesthetized with inhaled isoflurane delivered through a calibrated vaporizer or with an intraperitoneal injection of ketamine‑xylazine, dosing according to body weight. Adjustments are made to maintain a surgical plane of anesthesia while monitoring respiratory rate and reflexes.
How do you anesthetize a rat? - in detail
Administering anesthesia to a laboratory rat requires careful preparation, precise dosing, and continuous monitoring. The procedure can be divided into three phases: pre‑induction, induction and maintenance, and recovery.
Pre‑induction
- Verify that all equipment (anesthetic vaporizer, induction chamber, scavenging system, heating pad, monitoring devices) is functional and calibrated.
- Calculate drug dosage based on body weight; typical weight range for adult rats is 200–300 g.
- Prepare sterile injection syringes or fill vaporizer with the chosen agent.
- Fast the animal for 2–4 hours if injectable anesthetics are used, unless contraindicated.
Induction and maintenance
- For inhalational anesthesia, place the rat in a sealed induction chamber supplied with 2–5 % isoflurane in oxygen (1 L min⁻¹). Observe loss of righting reflex within 30–60 seconds.
- For injectable protocols, administer a mixture of ketamine (80 mg kg⁻¹) and xylazine (10 mg kg⁻¹) intraperitoneally. Expect surgical plane of anesthesia after 5–10 minutes.
- Confirm depth of anesthesia by evaluating pedal withdrawal reflex, palpebral reflex, and respiratory rate.
- Maintain anesthesia with a continuous flow of isoflurane (1–2 %) or supplemental injections of half‑dose ketamine/xylazine at 30‑minute intervals.
- Keep body temperature at 37 °C using a heating pad; monitor temperature with a rectal probe.
- Record heart rate, oxygen saturation, and respiration using a pulse oximeter or a small animal monitor.
Recovery
- Discontinue anesthetic gas or cease supplemental injections.
- Transfer the rat to a warmed recovery cage with a soft bedding surface.
- Observe until the animal regains the righting reflex and normal gait, typically within 10–20 minutes for inhalational agents, longer for injectable combinations.
- Provide analgesia (e.g., buprenorphine 0.05 mg kg⁻¹ subcutaneously) as required.
- Document all parameters, including drug lot numbers, concentrations, and any adverse events.
Adherence to aseptic technique, proper waste disposal, and institutional animal care guidelines ensures both experimental integrity and animal welfare.