Effect of multilevel laboratory rat caging system on the well-being of the singly-housed Sprague Dawley rat.

Current regulations emphasize that good husbandry practices allow animals to engage in species appropriate postural adjustments without touching the enclosure walls. This study evaluated the well-being of rats housed in a commercially available multilevel rat caging system, with or without access to the upper level of the caging. The evaluation methodologies included assessment of behavioral observations in the home cage, physiological assessment of metabolism and immune function, and determination of the affective state using a spatial cognitive bias assay. The study determined that rats that were provided access to the full multilevel cage during testing after initial restriction to the lower level of the cage demonstrated behavioral changes consistent with a positive affective state, while those with no changes to their housing situation had no significant differences in their affective states. Rats that were consistently housed with access restricted to the lower level of the cage exhibited a tendency to increased neutrophil:lymphocyte ratios as compared with those provided with access to all levels of the multilevel cage. There were no differences in body weight demonstrated between the experimental groups. Overall use of the cage space, as documented through analysis of behavioral observations in the home cage, demonstrated no significant differences in preferred location in the cage during the light or dark cycles, though rats with access to both levels of the cage were significantly more active during the light cycle. The results of this study suggest that the use of a multilevel caging system may improve the well-being of rats used in research.

Effects of space allocation and housing density on measures of wellbeing in laboratory mice: a review.

In the majority of countries where there are legislative requirements pertaining to the use of animals in research, figures are quoted for minimum cage sizes or space allocation to be provided per animal. These figures are generally based on professional judgement and are in common usage. However, there is a growing trend and expectation that welfare science should inform regulatory decision-making. Given the importance of the potential welfare influences of cage size on the animals themselves, this paper presents the latest scientific knowledge on this topic in one of the most commonly used animals in research, the mouse. A comprehensive review of studies in laboratory mice was undertaken, examining the effects of space allocation per animal and animal density on established welfare indicators. To date, animal density studies have predominated, and the effects of space allocation per se are still relatively unclear. This information will guide those involved in facility management or legislative review, and provide a more solid foundation for further studies into the effects of routine husbandry practices on animal welfare.