How can you sedate a mouse? - briefly
Administer a short‑acting anesthetic such as isoflurane via a calibrated vaporizer or inject a ketamine (50‑100 mg/kg) and xylazine (5‑10 mg/kg) mixture intraperitoneally, monitoring depth and body temperature. Follow institutional animal‑care protocols and calculate doses based on the mouse’s weight.
How can you sedate a mouse? - in detail
Effective sedation of a laboratory mouse requires precise selection of anesthetic agents, accurate dosing, appropriate delivery method, and continuous physiological monitoring. The process can be divided into preparation, induction, maintenance, and recovery phases.
Preparation begins with confirming the animal’s weight, health status, and any prior exposure to anesthetics. Record the exact weight to calculate drug dosage in milligrams per kilogram. Assemble a clean work surface, calibrated syringes, a warming pad, and a pulse oximeter or respiratory monitor. Ensure all equipment is sterilized and that a reversal agent is readily available.
Induction agents commonly employed include:
- Isoflurane: Vaporized in a calibrated vaporizer, delivered via a sealed induction chamber at 3–5 % concentration in oxygen for 1–2 minutes, then reduced to 1–2 % for maintenance.
- Ketamine‑xylazine mixture: Intraperitoneal injection of ketamine (80–100 mg/kg) combined with xylazine (5–10 mg/kg). Provides surgical depth within 5–10 minutes.
- Medetomidine: Subcutaneous injection at 0.1–0.3 mg/kg, often paired with low‑dose ketamine to enhance sedation and analgesia.
- Propofol: Intravenous bolus of 10–15 mg/kg via tail vein, suitable for short procedures requiring rapid onset and recovery.
Dosage calculations must be performed for each mouse individually. For example, a 25‑g mouse receiving ketamine‑xylazine would be administered 2 mg ketamine and 0.125 mg xylazine, diluted in sterile saline to a total volume of 0.1 ml.
During maintenance, adjust the anesthetic concentration or provide supplemental injections to sustain a stable plane of anesthesia. Monitor respiratory rate, heart rate, and body temperature at least every five minutes. Apply a heating pad set to 37 °C to prevent hypothermia, which can alter drug metabolism.
Recovery is facilitated by:
- Discontinuing inhalant agents and supplying 100 % oxygen for 2–3 minutes.
- Administering reversal agents: atipamezole (0.5 mg/kg) for medetomidine, or flumazenil (0.1 mg/kg) for benzodiazepine‑based protocols.
- Observing the animal until righting reflex returns and normal ambulation resumes, typically within 10–20 minutes for injectable regimens.
Safety and ethical considerations include:
- Using the minimal effective dose to reduce physiological stress.
- Maintaining aseptic technique to avoid infection.
- Documenting all drug lot numbers, concentrations, and timing of administration.
- Ensuring compliance with institutional animal care guidelines and obtaining appropriate approvals before any procedure.
By adhering to these systematic steps, researchers can achieve reliable, reproducible sedation of mice while minimizing adverse effects and ensuring animal welfare.