Effects of cage size and environmental enrichment on organ weight and leukocyte distribution in C57BL/6, BALB/c and CD-1 mice (2006)

Forsyth, N. Y., Kendall, L. V., Mench, J. A.

Abstract

Female mice from 3 strains were housed in polycarbonate cages each containing 4 same-strain mice under one of the following conditions: small (58cm2 per mouse) unenriched cage, small enriched cage, medium (96.8 cm2 per mouse) unenriched cage, medium enriched cage, large (219.4 cm2 per mouse) unenriched cage, and large enriched cage. There was no effect of enrichment on WBC counts, but there were significant interactions between strain and cage size for total WBC counts, lymphocytes, and monocytes. In BALB/c mice, total WBC counts, lymphocyte, and monocyte counts all decreased linearly with decreasing cage size. These results show that cage size affects leukocyte profiles that may be indicative of a stress response, and that these effects are strain dependent.