A comparison of rodent caging systems based on microenvironmental parameters

Area of Science:

• Laboratory animal science
• Comparative physiology
• Environmental monitoring

Background:

• Standardized housing is crucial for animal welfare and research reproducibility.
• Microenvironmental conditions within rodent cages can influence physiological parameters.
• Assessing the impact of different caging systems on key environmental factors is essential.

Purpose of the Study:

• To evaluate four mouse caging systems for microenvironmental parameters.
• To compare temperature, carbon dioxide, relative humidity (RH), and ammonia levels.
• To determine the influence of filter types and housing conditions.

Main Methods:

• Four caging systems with polycarbonate bases and different filter lids (molded polyester, two polycarbonate types, none) were tested over 7 days.
• Microenvironmental parameters (temperature, CO2, RH, ammonia) were monitored.
• Studies varied macroenvironmental RH, bedding, mouse strain, and filter grades.

Main Results:

• All systems maintained stable intracage temperatures (75.5°F ± 0.5°F).
• Polycarbonate filter lids resulted in significantly higher carbon dioxide levels (>2200 ppm increase).
• Polycarbonate and molded polyester lids increased RH compared to controls; polycarbonate systems showed detectable ammonia by day 6 (>200 ppm), while controls had none.

Conclusions:

• Caging system design, particularly filter type, significantly affects microenvironmental conditions.
• Polycarbonate filter lids can lead to detrimental increases in ammonia and carbon dioxide.
• Careful selection of mouse caging is necessary to ensure optimal animal welfare and experimental validity.