The importance of burrowing, climbing and standing upright for laboratory rats

Abstract

Standard laboratory cages prevent rats (Rattus norvegicus) from performing many behaviours that they perform in the wild, but little is known about how this may affect their welfare. The aims of this study were (i) to record the propensity to burrow, climb and stand upright in 3-, 8- and 13-month old laboratory rats housed in semi-naturalistic environments and (ii) to compare the frequency of lateral stretching in semi-naturalistic versus standard-housed rats; we predicted standard-housed rats would perform more lateral stretches to compensate for the inability to stretch upright. Rats' propensity to burrow remained constant as they aged (approx. 30 bouts per day totalling 20–30 min), suggesting burrowing is important to rats. Climbing decreased from 76 to 7 bouts per day at 3 versus 13 months, probably because of declining physical ability. Upright standing decreased from 178 to 73 bouts per day, but continued to be frequently expressed even in older rats. Standard-housed rats stretched much more frequently than semi-naturalistic-housed rats (53 versus 6 bouts per day at 13 months), perhaps in compensation for inability to stretch upright and to relieve stiffness caused by low mobility associated with standard housing. These findings suggest that standard laboratory cages interfere with important natural behaviours, which is likely to compromise rat welfare.

A gravity-based three-dimensional compass in the mouse brain

“…Tilt and 3D orientation tuning had previously only been identified in aerial (bats) and tree-dwelling (macaques) species, raising the question of whether a 3D compass would be ethologically relevant to rodents. Although laboratory mice ( Mus musculus ) and rats ( Rattus norvegicus ) are primarily land-dwelling, they exhibit a rich 3D behavioral repertoire (Makowska and Weary 2016; Mimica et al 2018) in the wild living in extensive underground burrows (Schmidt and Fischer 2011) and easily learn 3D spatial orientation tasks (Wilson et al 2015). Furthermore, laboratory mice and rats are physiologically related to tree-dwelling rodents (Arregoitia et al 2017), including other muroids (e.g.…”

A gravity-based three-dimensional compass in the mouse brain

“…Tilt and 3D orientation tuning had previously only been identified in aerial (bats) and tree-dwelling (macaques) species, raising the question of whether a 3D compass would be ethologically relevant to rodents. Although laboratory mice (Mus musculus) and rats (Rattus norvegicus) are primarily landdwelling, they exhibit a rich 3D behavioral repertoire in the wild [50][51][52] , easily learn 3D spatial orientation tasks 53 and are physiologically related to tree-dwelling rodents 54 , including other muroids (e.g. harvest mice, Micromys minutus) and nonmuroids (e.g.…”

Behavioral Research on Captive Animals: Scientific and Ethical Concerns

“…For example, sporadic noise stress administered to rats can encourage the display of abnormal rearing behavior, as well as impact their gut morphology (Baldwin, Primeau and Johnson, 2006) and the functioning of their autonomic nervous system (Burwell and Baldwin, 2006), among other stress-related diseases (Gaskill, 2016). In addition, being prevented from performing one's natural behavior can result in reduced physiological condition (Makowska and Weary, 2016). Overall, animals living in the laboratory are vulnerable to abnormal behavior, physiology, and brain development.…”

“…Although laboratory behavioral research may rarely come under the category of causing "severe" suffering (unless being carried out alongside invasive procedures), for ethology studies; we have seen, from the first part of this chapter, that some experimental methods cause animals to experience psychological stress to such a degree that it can affect their long-term physiological development. Even simply living in a laboratory environment can result in a sufficient amount of stress to bring about permanent changes in behavior, physiology, and brain development (e.g., Makowska and Weary, 2016;van Praag, Kempermann and Gage, 2000;Würbel, 2001). Ultimately, a laboratory can never adequately provide an environment for an animal to behave in an ecologically relevant way for experimental findings to inform about natural behavior or evolved abilities.…”