Which method is considered acceptable for euthanizing mice?

• A. Injection with barbiturates.
• B. CO2 inhalation.
• C. Decapitation.
• D. Freezing.

Answer: (A)

The method being tested emphasizes humane euthanasia by rapidly achieving unconsciousness and death with minimal distress. Injecting a barbiturate overdose accomplishes this quickly when performed by a trained person, with the dose aimed to ensure a humane and predictable outcome. This direct, pharmacological approach tends to minimize struggling and suffering, which is why it is considered acceptable under standard laboratory animal welfare guidelines.

CO2 inhalation can also be used under specific protocols, but it requires careful control of concentration and flow to avoid initial aversion or distress, so it is not as straightforward as an injectable overdose. Decapitation and freezing are generally not considered humane euthanasia methods because they can cause significant pain or prolonged distress before death.