Effects of Extended Cage Component Sanitation Interval on the Microenvironment, Health, and Gastrointestinal Microbiome of Rats (Rattus norvegicus)

Washing and sanitizing rodent cage components requires costly equipment, significant personnel effort, and use of natural resources. The benchmark frequency for sanitation of individually ventilated caging (IVC) has traditionally been every 2 wk. In this study, we investigated the effects of extending this interval on the cage microenvironment, basic markers of health, and the gastrointestinal microbiota of rats. We compared our institutional standard of changing the sanitation interval for rat cage lids, box feeders, and enrichment devices from every 4 wk to an interval of 12 wk. The cage bottom and bedding continued to be changed every 2 wk for both groups. We hypothesized that we would find no significant difference between our current practice of 4 wks and continuous use for 12 wk. Our data showed that intracage ammonia levels remained below 5 ppm for most cages in both groups, with the exception of cages that experienced a cage flood. We found no significant difference between groups in bacterial colony forming units (CFU) on cage components. We used 3 novel methods of assessing cleanliness of enrichment devices and found no significant effect of continuous use for 12 wk on the number of CFU. In addition, we found no significant differences between groups for animal weight, routine blood work, or fecal and cecal microbiomes. These data indicate that a sanitation interval of up to 12 wk for components of rat IVC caging has no significant effects on the microenvironment or health of rats. Using the longer interval will improve efficiency, reduce the use of natural resources, and decrease costs while maintaining high-quality animal care.