Automated Analysis of Homecage Lid Interaction and Hanging Behaviour as a Measure of Pain in Mice

Most rodent studies of pain rely on the use of experimenter-evoked measures of pain and assess behavior under ethologically unnatural conditions, which limits the translational potential of preclinical research. We approached this problem by conducting an unbiased, prospective study of behavioral changes in mice within a natural homecage environment using conventional preclinical pain assays. We observed that cage lid hanging, a species-specific elective behavior, was the only homecage behavior reliably impacted by pain assays. Noxious stimuli reduced hanging behavior in an intensity-dependent manner, and the reduction in hanging could be rescued by analgesics. Finally, we developed an automated approach to assess hanging behavior. This demonstration will review the utility and limitations of studying homecage behaviors for the assessment of pain and describe technologies to automate the measurement of cage lid interaction.