Effects of nominal differences in cage height and floor space on the wellbeing of rabbits

The 8th edition of the Guide for the Care and Use of Laboratory Animals recommends a cage height of 16 in. for rabbits, compared with 14 in. in the previous edition. In contrast, the Animal Welfare Act Regulations prescribes a cage height of 14 in. for rabbits. A review of the literature failed to identify published data that support an advantage to rabbits having 16 in. of cage height compared with 14 or 15 in. The study described here evaluated the effect of a 3-in. difference in cage height on the health, growth, behavior, and overall wellbeing of rabbits. Groups of 10 New Zealand white rabbits were housed in cages that provided either 15 in. of interior cage height (720in² of floor space) or 18 in. of interior height (784 in2 of floor space). The rabbits were observed during 25 periods (1 h each) over 7 wk, and various behavioral parameters were scored. In addition, rabbits were weighed weekly, and general clinical health was assessed. After 4 wk, the groups were switched to the alternate housing. No significant differences in body weight gain or behavioral parameters were detected between groups housed in cages with different heights and amounts of floor space, nor were significant behavioral differences noted in individual rabbits when moved from one cage type to the other. In addition, all rabbits remained clinically healthy throughout the study. These results demonstrate that these differences in interior cage height neither benefit nor harm rabbits.