Automated mouse euthanasia in an individually ventilated caging system: system development and assessment.

Area of Science:

• Laboratory Animal Science
• Veterinary Medicine
• Animal Welfare

Background:

• Current methods for large-scale rodent euthanasia can be labor-intensive and pose challenges in maintaining consistent conditions.
• There is a need for automated, safe, and humane systems for euthanizing large numbers of laboratory animals.

Purpose of the Study:

• To develop and evaluate an automated, individually ventilated caging system for simultaneous CO2 euthanasia of up to 70 mouse cages.
• To assess the system's consistency, reproducibility, safety, and humane aspects in accordance with established guidelines.

Main Methods:

• Development of a logic-controlled, automated CO2 delivery system integrated into an individually ventilated caging setup.
• Evaluation of intracage CO2 levels, fill dynamics, and maximal concentrations under varying supply plenum pressures (0.35, 0.25, 0.15 in. H2O).
• Behavioral assessments of mice to evaluate distress levels at different plenum pressures and cage positions.

Main Results:

• The system demonstrated consistent and reproducible CO2 delivery, allowing visualization and integrating safety features.
• Intracage CO2 concentrations were influenced by both supply plenum pressure and cage position.
• No discernible differences in mouse distress were observed across different cage locations or plenum pressures.

Conclusions:

• The developed automated CO2 euthanasia system is safe, effective, and labor-saving for large-scale mouse euthanasia.
• The system is humane and compatible with recommendations for animal euthanasia, ensuring consistency and minimizing environmental contamination.