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

52 GUIdE FOR ThE CARE ANd USE OF LAbORATORy ANIMALStion (Peace et al. 2001). When given the choice, rodents prefer solid floors(with bedding) to grid or wire-mesh flooring (Blom et al. 1996; Manser etal. 1995, 1996).Animals should have adequate bedding substrate and/or structuresfor resting and sleeping. For many animals (e.g., rodents) contact beddingexpands the opportunities for species-typical behavior such as foraging,digging, burrowing, and nest building (Armstrong et al. 1998; Ivyet al. 2008). Moreover, it absorbs urine and feces to facilitate cleaningand sanitation. If provided in sufficient quantity to allow nest buildingor burrowing, bedding also facilitates thermoregulation (Gordon 2004).Breeding animals should have adequate nesting materials and/or substitutestructures based on species-specific requirements (mice: Sherwin 2002;rats: Lawlor 2002; gerbils: Waiblinger 2002).Specialized housing systems (e.g., isolation-type cages, IVCs, and gnotobiotic1isolators) are available for rodents and certain species. Thesesystems, designed to minimize the spread of airborne particles betweencages or groups of cages, may require different husbandry practices, such asalterations in the frequency of bedding change, the use of aseptic handlingtechniques, and specialized cleaning, disinfecting, or sterilization regimensto prevent microbial transmission by other than airborne routes.Appropriate housing strategies for a particular species should be developedand implemented by the animal care management, in consultationwith the animal user and veterinarian, and reviewed by the IACUC. Housingshould provide for the animals’ health and well-being while beingconsistent with the intended objectives of animal use. Expert advice shouldbe sought when new species are housed or when there are special requirementsassociated with the animals or their intended use (e.g., geneticallymodified animals, invasive procedures, or hazardous agents). Objectiveassessments should be made to substantiate the adequacy of the animal’senvironment, housing, and management. Whenever possible, routine proceduresfor maintaining animals should be documented to ensure consistencyof management and care.Enironmental EnrichmentThe primary aim of environmental enrichment is to enhance animalwell-being by providing animals with sensory and motor stimulation,through structures and resources that facilitate the expression of speciestypicalbehaviors and promote psychological well-being through physical1Gnotobiotic: germ-free animals or formerly germ-free animals in which the compositionof any associated microbial flora, if present, is fully defined (Stedman’s Electronic MedicalDictionary 2006. Lippincott Williams & Wilkins).