Abstract
This study compared behavioral and physiologic changes in Sprague-Dawley and Brown Norway rats that were euthanized by using a 30% volume displacement rate of CO₂ in either their home cage or an induction chamber; rats euthanized in the home cage were hypothesized to demonstrate a higher level of animal wellbeing. No significant differences were detected in the physiologic responses to home cage versus induction chamber euthanasia groups. A few strain-related behavioral differences occurred. The number of digs per second was higher in Brown Norway compared with Sprague-Dawley rats when in the home cage, where a digging substrate was present. Rearing frequency was higher in both Brown Norway and Sprague-Dawley rats in the induction chamber compared with the home cage. This study demonstrated that although strainspecific differences were associated with the process of euthanasia, there were no significant differences between the treatment groups of home cage compared with induction chamber. This finding suggests that-from the perspective of a rat-either the home cage or an induction chamber can be used for euthanasia, with likely extension of this conclusion to use of either method to the induction of anesthesia.