The Hidden Costs of Housing Practices: the importance of murine cold-stress to science

Laboratory mice housed in modern vivariums are chronically cold-stressed. Cold-stressed mice exhibit compensatory non-shivering thermogenesis that drives a significant increase in total energy expenditure. In this manuscript, we will describe the visualization andquantification of non-shivering thermogenesis with thermography as a metric of murine cold-stress (Chapter 2). Utilizing thermography to measure cold-stress within the vivarium, we will show mice housed in individually ventilated caging, a popular and important housing system,exhibit significantly greater non-shivering thermogenesis than mice housed in static cages. Xenograft tumors implanted in mice housed in individually ventilated cages have blunted growth and metabolism compared to static cages. The experimental variability between housingsystems can be significantly, but incompletely, mitigated by the addition of shelters that allow mice to maintain heated micro-climates (Chapter 3). Housing dependent variations in experimental results is likely a confounder throughout murine dependent research. We designed and validated novel ventilated caging designed to minimize the chilling effects of individually ventilated cages while preserving the benefits of ventilated caging (Chapter 4)