Purpose
The purpose of this policy is to describe appropriate frequency of cage changes for rodents housed at the University of Washington (UW)
Background
According to the Guide, “The frequency and intensity of cleaning and disinfection should depend on what is needed to provide a healthy environment for an animal. Methods and frequencies of sanitation will vary with many factors…” The recommended frequency stated in the Guide for sanitation of rodent primary enclosure wire tops, food holders and filter tops is at least once every two weeks. The Guide also states that some types of cages and racks, such as individually ventilated cages, might require less frequent cleaning and disinfection. A study that used similar cages and bedding as used at the University of Washington2, found no difference in organic contamination or bacterial colonies on rodent caging accessories at 2 weeks versus several months of use. An internal study, presented to the IACUC at the December 13, 2012 meeting, found similar findings to the Schondelmeyer study, with no significant increase in organic contamination in a 4 week period. An internal study, presented to the IACUC at the February 20, 2020 meeting, determined no significant increase in ammonia or evidence of excessively soiling after 28 days in singly housed gerbils in static cages. The optimal sanitation schedule is one that is frequent enough to maintain cleanliness and prevent disease, while providing minimal disruption to the rodent microenvironment.
Policy
Standard SPF rodent housing of healthy mice and rats in static cages requires a change frequency of a minimum of once a week for mice and once or twice a week for rats, depending on the size and number of rats per cage. Individually-ventilated cages require sanitation of the cages at least once every 14 days and sanitation of the cage wire tops, food holders and filter tops at least every four weeks. For singly housed gerbils, the entire static cage set-up will be changed at least once every 28 days. These frequencies must be increased if cages or cage accessories become soiled, during disease outbreaks, or for other conditions determined appropriate by the Attending Veterinarian.
References
- Guide for the Care and Use of Laboratory Animals, Eighth Edition, NRC, 2011, pp 69-70.
- Schondelmeyer et al. (2006) Investigation of appropriate sanitization frequency for rodent caging accessories: evidence supporting less-frequent cleaning. J Am Assoc Lab Anim Sci. 45(6):40-3.
Approval/Review Dates
Originally Approved: 09/17/2009
Last Reviewed/Revised by the IACUC: 11/18/2021