Performance Validated 8-Week Sanitation Interval for Mouse (Mus musculus) Wire-Bar Lids: ATP and CFU Outcomes

Frequent sanitation of rodent cage accessories is labor-intensive and costly. The Guide for the Care and Use of Laboratory Animals recommends changing tops every 2 weeks but allows performance-based intervals when supported by data. This study evaluated whether mouse wire-bar lid sanitation intervals can be extended to 8 weeks without increasing organic or microbial load. In a 10-week study across 5 cage configurations, wire-bar lids were sampled at weeks 0, 2, 4, 6, 8, and 10. Organic residue was quantified by ATP luminometry (relative light units [RLUs]) and viable bioburden by total plate count (TPC; CFU/cm2) using Hygicult TPC contact agar. Prespecified action thresholds were ATP ≤100,000 RLU and TPC ≤45 CFU/cm2. All values remained below thresholds; ATP was consistently <5% of the action level and TPC maxima <40% of the action level. Two one-sided tests on log-transformed data demonstrated biologic equivalence between week 8 and week 2 across all configurations, with 90% CIs fully within prespecified margins (±10,000 RLU; ±4.5 CFU/cm2). Under these conditions, extending the wire-bar lid sanitation interval to 8 weeks was feasible without evidence of increased organic load or bioburden. Based on facility census and time-and-motion data, the change is projected to save ∼22,075 kWh/y of energy, 166,270 L/y of water, and ∼1,125 labor hours (≈0.54 full-time equivalent). These findings provide site-specific validation supporting performance-based sanitation intervals for wire-bar lids. Implementation should remain performance-validated and site-specific. Future studies may assess other cage components and microenvironmental parameters to support performance-based intervals across the home-cage system.