Effect of castration on rabbits housed in littermate pairs.

Conventional solitary caging for research rabbits precludes many postural and social behaviors. Several studies that have investigated enrichment strategies for rabbit does have found intact males usually too aggressive for paired or group housing. This study investigated the possibilities that male siblings will remain compatible if never separated from birth and that castration will improve compatibility among young sibling male rabbits. As a side benefit of pair housing for all rabbits, the larger cages (modified dog cages) allowed rest and other postures not possible in conventional single cages. In addition, there was no evidence of the stereotypies observed among individually housed rabbits. Castrated, post-weanling, male, Flemish Giant x Giant Chinchilla rabbit littermates demonstrated a significantly higher level of living together compatibly than did the intact controls. All rabbits chose to rest in close proximity or contact, although this preference was stronger in castrated males. During puberty, intact males displayed more serious aggression. We conclude that young adult littermate rabbits can live compatibly as pairs and that castration improves compatibility among males. Paired rabbits exhibit many postures and behaviors that are not possible in the small, solitary cages currently listed as minimum recommendations.