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

58 GUIdE FOR ThE CARE ANd USE OF LAbORATORy ANIMALSanimal may be required, while larger groups may be housed at slightlyhigher densities.Studies have recently evaluated space needs and the effects ofsocial housing, group size, and density (Andrade and Guimaraes 2003;Bartolomucci et al. 2002, 2003; Georgsson et al. 2001; Gonder and Laber2007; Perez et al. 1997; A.L. Smith et al. 2004), age (Arakawa 2005;Davidson et al. 2007; Yildiz et al. 2007), and housing conditions (Gordonet al. 1998; Van Loo et al. 2004) for many different species and strains ofrodents, and have reported varying effects on behavior (such as aggression)and experimental outcomes (Karolewicz and Paul 2001; Laber et al. 2008;McGlone et al. 2001; Rock et al. 1997; Smith et al. 2005; Van Loo et al.2001). However, it is difficult to compare these studies due to the studydesign and experimental variables that have been measured. For example,variables that may affect the animals’ response to different cage sizes andhousing densities include, but are not limited to, species, strain (and socialbehavior of the strain), phenotype, age, gender, quality of the space (e.g.,vertical access), and structures placed in the cage. These issues remaincomplex and should be carefully considered when housing rodents.Other Common Laboratory Animals Tables 3.3 and 3.4 list recommendedminimum space for other common laboratory animals and for avian species.These allocations are based, in general, on the needs of pair- orgroup-housed animals. Space allocations should be reevaluated to providefor enrichment or to accommodate animals that exceed the weights in thetables, and should be based on species characteristics, behavior, compatibilityof the animals, number of animals, and goals of the housing situation(Held et al. 1995; Lupo et al. 2000; Raje 1997; Turner et al. 1997). Singlyhoused animals may require more space per animal than that recommendedfor group-housed animals, while larger groups may be housed atslightly higher densities. For cats, dogs, and some rabbits, housing enclosuresthat allow greater freedom of movement and less restricted verticalspace are preferred (e.g., kennels, runs, or pens instead of cages). Dogs andcats, especially when housed individually or in smaller enclosures (Bayne2002), should be allowed to exercise and provided with positive humaninteraction. Species-specific plans for housing and management shouldbe developed. Such plans should also include strategies for environmentalenrichment.Nonhuman Primates The recommended minimum space for nonhuman primatesdetailed in Table 3.5 is based on the needs of pair- or group-housedanimals. Like all social animals, nonhuman primates should normally havesocial housing (i.e., in compatible pairs or in larger groups of compatibleanimals) (Hotchkiss and Paule 2003; NRC 1998a; Weed and Watson 1998;