Guide for the Care and Use of Laboratory Animals - Office of ...

ENVIRONMENT, hOUSING, ANd MANAGEMENT 51physical, physiologic, and behavioral needs. Environments that fail to meetthe animals’ needs may result in abnormal brain development, physiologicdysfunction, and behavioral disorders (Garner 2005; van Praag et al. 2000;Würbel 2001) that may compromise both animal well-being and scientificvalidity. The primary enclosure or space may need to be enriched to preventsuch effects (see also section on Environmental Enrichment).An appropriate housing space or enclosure should also account forthe animals’ social needs. Social animals should be housed in stable pairsor groups of compatible individuals unless they must be housed alone forexperimental reasons or because of social incompatibility (see also sectionon Behavioral and Social Management). Structural adjustments are frequentlyrequired for social housing (e.g., perches, visual barriers, refuges),and important resources (e.g., food, water, and shelter) should be providedin such a way that they cannot be monopolized by dominant animals (seealso section on Environmental Enrichment).The primary enclosure should provide a secure environment that doesnot permit animal escape and should be made of durable, nontoxic materialsthat resist corrosion, withstand the rigors of cleaning and regular handling,and are not detrimental to the health and research use of the animals.The enclosure should be designed and manufactured to prevent accidentalentrapment of animals or their appendages and should be free of sharpedges or projections that could cause injury to the animals or personnel.It should have smooth, impervious surfaces with minimal ledges, angles,corners, and overlapping surfaces so that accumulation of dirt, debris, andmoisture is minimized and cleaning and disinfecting are not impaired. Allenclosures should be kept in good repair to prevent escape of or injury toanimals, promote physical comfort, and facilitate sanitation and servicing.Rusting or oxidized equipment, which threatens the health or safetyof animals, needs to be repaired or replaced. Less durable materials, suchas wood, may be appropriate in select situations, such as outdoor corrals,perches, climbing structures, resting areas, and perimeter fences for primaryenclosures. Wooden items may need to be replaced periodically becauseof damage or difficulties with sanitation. Painting or sealing wood surfaceswith nontoxic materials may improve durability in many instances.Flooring should be solid, perforated, or slatted with a slip-resistant surface.In the case of perforated or slatted floors, the holes and slats shouldhave smooth edges. Their size and spacing need to be commensurate withthe size of the housed animal to minimize injury and the developmentof foot lesions. If wire-mesh flooring is used, a solid resting area may bebeneficial, as this floor type can induce foot lesions in rodents and rabbits(Drescher 1993; Fullerton and Gilliatt 1967; Rommers and Meijerhof 1996).The size and weight of the animal as well as the duration of housing onwire-mesh floors may also play a role in the development of this condi-