Should Large Rats Be Housed in Large Cages? An Empirical Issue

The Canadian Council on Animal Care (CCAC) has recently started to suggest that large rats should be kept in cages that are 23 cm high, rather than in the 17.5 to 18 cm high cages that are currently standard throughout North America. In the present experiment, eight large rats (489 to 623 g) were each allowed to choose for 24 hr between a 16.8-cm-high cage and a 23-cm-high cage. The rats failed to exhibit any preference for the higher cage. It is suggested that before the CCAC mandates commitment of substantial resources for a change in the conditions of laboratory animal maintenance, some objective evidence should be provided that the proposed change improves the well being of animals.