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Policy#: 529-274

Title: ANIMAL CARE / VIVARIA ISSUES: Wire Bottom Cages for Housing Rodents

Effective: 5/18/2022



It is expected that solid-bottom cages will be used as the default, but wire bottom cages are acceptable if a sound scientific rationale for their use in a study has been reviewed and approved by the IACUC. Surplus animals or animals not on approved studies should be housed in solid-bottom cages.  

The use of wire bottom cages can lead to the development of foot problems in heavier animals after long term housing in these cages. Another issue is animal preference. The Guide notes that several studies provide evidence that solid-bottom caging with bedding is preferred by rodents and thus recommends this type of housing for rodents. The Guide states it is the responsibility of the IACUC to ensure that housing meets the highest husbandry standards considered appropriate for the health and well-being of the research animal and consistent with the research objectives.  


All rodents should be housed in solid-bottom cages. Breeding animals must always be housed in solid-bottom cages.  

Use of wire-bottom cages may be approved if the use of solid-bottom caging is contraindicated by the research protocol and scientifically justified. The scientific justification for use of wire-bottom cages must be within the protocol approved by the IACUC. All animals that are not directly involved in a study must be housed in solid-bottom cages.  

Rodents greater than 500 grams held on wire must be checked at least weekly for foot problem.  


1. The Guide for the Care and Use of Laboratory Animals, 8th edition, 2011. 

Updated: 12/9/04; 4/18/2022