Chu, L., Garner, J. P., Mench, J. A. 2004. A behavioral comparison of New Zealand White rabbits (Oryctolagus cuniculus) housed individually or in pairs in conventional laboratory cages. Applied Animal Behaviour Science 85, 121-139.

We compared the behavior of female New Zealand White rabbits (Oryctolagus cuniculus) housed either individually (N=4) in cages measuring 61 cmx76 cmx41 cm or in non-littermate pairs (four pairs) in double-wide cages measuring 122 cmx76 cmx41 cm. .. Over the 5 months, individually housed rabbits showed an increase in the proportion of the total behavioral time budget spent engaged in abnormal behaviors (digging, floor chewing, bar biting), from 0.25 to 1.77%, while pairs remained unchanged at 0.95% . .. Paired rabbits engaged in more locomotor behavior (F1,6=16.49; P<0.0066) than individual rabbits (average proportions of time budget: 2.71 and 0.70% for paired andindividual rabbits, respectively), which may be important because caged rabbits are susceptible to osteoporosis and other bone abnormalities due to the restricted ability to move. Time spent feeding and body weights of dominant and subordinate rabbits in a pair did not differ, indicating that food competition was not a problem, and paired rabbits were often observed in physical contact (26.7% of data records) although the size of the cages allowed physical separation. Aggression between pairmates did not increase significantly during the study. However, one pair did have to be separated at the end of the study due to bite wounds from persistent aggression. Thus, although methods for decreasing injurious aggression require further investigation, the beneficial effects of pair housing in decreasing abnormal behaviors and increasing locomotion suggest that pair housing should be considered as an alternative to individual housing for caged laboratory rabbits.