How should a mouse be properly killed? - briefly
A rapid cervical dislocation performed by trained personnel instantly severs the spinal cord, causing immediate loss of consciousness. Alternatively, exposure to a calibrated CO₂ flow that reaches 70 % concentration within seconds provides a humane, painless death.
How should a mouse be properly killed? - in detail
When a laboratory mouse must be euthanized, the method chosen should ensure rapid loss of consciousness, minimal pain, and compliance with accepted animal welfare standards. The following procedures are widely recognized as humane and effective.
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Carbon dioxide inhalation: Fill a calibrated chamber with CO₂ at a flow rate of 30 % of the chamber volume per minute. Allow the concentration to rise gradually to 70 % before the animal loses consciousness. Maintain exposure until cardiac arrest is confirmed. This technique requires a gas‑delivery system with precise flow control and monitoring devices to avoid hypoxia before the target concentration is reached.
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Inhalant anesthetic overdose: Administer isoflurane or sevoflurane in a sealed container until the mouse exhibits a deep plane of anesthesia, followed by cessation of breathing. Use a vaporizer to deliver the agent at 5 %–6 % concentration in oxygen. Verify death by checking for absence of pulse and reflexes.
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Intraperitoneal injection of a barbiturate: Inject a dose of sodium pentobarbital (150 mg/kg) into the abdominal cavity. The drug induces rapid unconsciousness and respiratory depression, leading to cardiac arrest within minutes. Ensure the solution is sterile and that the injection site is free of contamination.
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Cervical dislocation: Perform a swift, controlled separation of the cervical vertebrae using thumb and forefinger pressure at the base of the skull. This method requires training to execute correctly and is suitable only for small rodents when performed by experienced personnel.
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Physical decapitation: Use a sharp guillotine or specialized rodent decapitation device. The cut must be instantaneous, severing the spinal cord and brainstem. Apply immediately after a brief anesthetic exposure to guarantee unconsciousness prior to the procedure.
Each technique demands the following safeguards: verification of death through absence of heartbeat, respiration, and corneal reflex; documentation of the method and dose; and disposal of carcasses according to biohazard regulations. Selection among these options should consider the experimental context, available equipment, and the need for tissue integrity for downstream analyses.