Housing environment influences the need for pain relief during post-operative recovery in mice

The impact of invasive experimental procedures on perceived stress and pain may be dependent on both physical and social environmental conditions. The aim of this study was to evaluate the effects of a physically and a socially enriched environment on the need for pain relief following painful experimental procedures. A non-invasive method to administer analgesics post-operatively is by means of self-administration which is a feasible objective method to measure perceived pain during the post-operative recovery period. In the present study eight groups of mice housed in different conditions underwent the surgical procedure of caecal manipulation or only exposure to anaesthesia. After surgery the mice were given the choice to self-administer an analgesic available in one of their water bottles during two post-operative weeks. It was shown that socially enriched mice drank i.e. self-administered, less from the analgesic containing water than the non-enriched and socially deprived groups. Mice that underwent operation self-administered more analgesic than mice that received only anaesthesia without operation. The findings indicate that the recovery environment can contribute positively to attenuate the need for pain relief in animals submitted to invasive procedures.