How should mice be killed? - briefly
The most widely accepted humane methods are carbon‑dioxide inhalation and injectable anesthetic agents, applied according to institutional animal‑care guidelines. All procedures must be performed by trained personnel and recorded in compliance with applicable regulations.
How should mice be killed? - in detail
Euthanasia of laboratory or pest mice requires methods that achieve rapid loss of consciousness, guarantee death without distress, and comply with ethical guidelines and legal regulations.
Carbon dioxide exposure is widely used for group euthanasia. A gradual fill of the chamber with CO₂ at a flow rate of 30 % of the chamber volume per minute prevents panic, produces unconsciousness within minutes, and avoids painful sensations. Continuous monitoring of gas concentration ensures the target level (approximately 70 % CO₂) is reached before the animals are removed.
For individual mice, injectable agents provide precise control. A dose of 150 mg kg⁻¹ sodium pentobarbital administered intraperitoneally induces unconsciousness within seconds, followed by cardiac arrest. Alternative agents include a combination of medetomidine (0.1 mg kg⁻¹) and ketamine (100 mg kg⁻¹) for rapid sedation, then a secondary injection of a barbiturate to complete the process. Injection sites must be disinfected, and needles replaced after each use to prevent cross‑contamination.
Physical methods are acceptable only when performed by trained personnel and when chemical options are unavailable. Cervical dislocation, executed with a swift, forceful motion, severs the spinal cord, resulting in immediate loss of brainstem activity. The technique requires proper positioning of the animal’s neck and a calibrated instrument to apply consistent force.
Inhalant anesthetics such as isoflurane can serve as a two‑step approach: induction of deep anesthesia followed by cessation of gas flow, leading to respiratory depression and death. The concentration must exceed 5 % in oxygen, and the animal’s breathing pattern should be observed to confirm the transition from anesthesia to irreversible cessation.
All procedures must be documented in compliance records, including the method, dosage, date, and personnel responsible. Personal protective equipment—gloves, lab coat, eye protection—protects handlers from exposure to chemicals and biological material. Waste disposal follows institutional biohazard protocols, with chemical agents rendered inert before incineration or appropriate chemical neutralization.
Selection of the method depends on the number of animals, available equipment, and regulatory requirements. The primary criteria remain rapid onset of unconsciousness, certainty of death, and minimization of pain and stress.