From house mouse to mouse house: the behavioural biology of free-living Mus musculus and its implications in the laboratory

Abstract

Understanding a species' behaviour in natural conditions can give insights into its development, responses and welfare in captivity. Here, we review research and pest control literatures on the free-living house mouse (Mus musculus), analysing its sensory world, developmental processes and behaviour to suggest how laboratory environments might affect mouse welfare, normalcy, test design, and behaviour. Mouse development from foetus to weaning is influenced by prenatal stress and nutrient levels, and post-natal litter size and other factors affecting maternal care, all with lasting effects on adult bodyweight, aggression, activity levels, stress responsiveness and masculinisation. These influences may well be important in the laboratory, for example unwittingly differing between facilities leading to site-differences in phenotype. Murine senses are dominated by olfactory, auditory and tactile cues. Their hearing extends into the ultrasonic, and vision, from mid-range wavelengths to the ultraviolet. In mouse facilities, behaviour and welfare may therefore also be affected by sensory stimuli unnoticed by humans. The physical and social environment and behaviour of wild mice differ greatly from those of laboratory mice. Dispersal age varies with resource-levels and social cues, and mice often either live alone or in family groups. Mice occupy territories/ranges measuring a few square meters to several square kilometers, and which allow running, climbing, and burrowing. Mice are often active during dawn/dusk, and spend their time patrolling their territories, investigating neighbours' odour cues, foraging, finding mates and rearing litters. The potential impact of these many differences and restrictions on laboratory mouse development, normalcy and welfare has only begun to be explored.

There's no place like home: Cage odours and place preference in subordinate CD-1 male mice

“…In their natural state, house mice (Mus domesticus) typically live in social groups (24,25,26,38,48). As would be expected, what evidence there is suggests that group housing promotes welfare in laboratories (20,61,64,65).…”

Differential Effects of Estrogen Receptor Alpha and Beta Specific Agonists on Social Learning of Food Preferences in Female Mice

“…Observer choice data were then expressed as a cinnamon preference ratio, that is, the amount of cinnamon diet eaten out of the total amount of food consumed (cinnamon/ (cocoa + cinnamon)), and arcsine transformed. A three-way mixed design analysis of variance (ANOVA) assessing the effects of demonstrated food, drug treatment, and time on the observers' cinnamon preference was not possible, as mice do not eat continuously throughout a 24 h period, but rather consume the majority of their food during the active, nocturnal phase of their light cycle (Latham and Mason, 2004;Figures 2 and 5). As a consequence, most of our mice failed to eat during at least one of the twelve 2 h intervals, and the presence of these empty cells in the data caused a repeated measure design to eliminate the majority of the sample.…”

Burrowing and nest building behavior as indicators of well-being in mice

“…Wild house mice build nests to 91 provide heat conservation, shelter from elements, predators, and competitors and to allow 92 successful reproduction (Deacon, 2006b;Hess et al, 2008;Latham and Mason, 2004). Nest 93 building increases lifetime reproductive success and is an essential thermoregulatory adaption 94 (Berry, 1970;Bult and Lynch, 1997).…”