Fuller, A. 2009. Successful pair housing of female New Zealand white rabbits. Tech Talk [The Newsletter for Laboratory Animal Science Technicians] 14(4), 2-3.

The veterinary staff at our facility has been working to pair house the female New Zealand white rabbits in our training colony. These rabbits range in size, age, and temperament, which can make finding potential partners difficult, especially since all are intact and have had little to no socialization with other rabbits prior to this point. Pair housing of female rabbits is made all the more difficult because little information is available on the topic. However, we were able to successfully pair rabbits in our laboratory, and hope our experiences may serve as a guide to other laboratories who are interested in pairing their rabbits. Female rabbits in the training colony were first given an extensive getting to know you period through several introduction sessions. Two females were chosen based on criteria such as size and general temperament (same tempered rabbits who are the same size are far more likely to get along) and were placed into an exercise pen together for at least 20 minutes a day for 2 weeks or longer. The floor under the pen was covered with textured cardboard to provide traction, and a disposable cardboard shelter was provided. Enrichment devices were also placed in the pen, including Jingle Balls and timothy hay cubes. During these introduction sessions, the rabbits were observed at all times. Expected behaviors include hyperpnea and chasing, as well as occasional vocalization and stomping. Mounting and hair pulling were also commonly seen;females engage in these behaviors in order to establish dominance. After several sessions, if the rabbits appeared to be more interested in confrontation than exploring their surroundings, the pair was separated. If any evidence of injury or extreme stress (dyspnea, pale ears) was seen, the rabbits were separated immediately. After each introduction session, the rabbits were returned to their regular housing. We swapped their feed hoppers and enrichment devices (shelters, toys) so that the rabbits would become accustomed to having the smell of their pair mates in their home cages. Rabbits were then given a timothy hay cube so that each session ended with positive reinforcement. At the conclusion of the 2-week introduction period, it was obvious which pairs were able to be successfully housed together; the expected behaviors listed above became less frequent, and positive signs such as nose touching and mutual grooming were observed. Pairing was performed at the start of a work day, on a rack-change day, so that neither rabbit had the chance to mark their territory. ... The divider between the two cages was pulled out halfway for the first 3 hours, which helped cut down on the amount of chasing the rabbits can do and allowed the rabbits to spend time apart until they became used to the new experience of having a cage mate. Each rabbit pair was also given a rabbit shelter. Sheltering is especially important on the first day of pair housing, as almost every rabbit shows apprehension during such a drastic change in their housing conditions. The shelter helps to alleviate stress during this time by providing a sanctuary if one rabbit wanted to be away from the other. If there were no unexpected adverse behaviors after 3 hours, the divider was removed.The pair-housed rabbits were observed several times a day for the first 3 days. The primary enclosure and pan liner were monitored for signs of fighting between animals. Body weights were measured every other day for 2 weeks; slight reductions in weight gain were to be expected, due to the potential stress and also the increased level of exercise that a rabbit receives while being pair housed. General body condition was assessed while the rabbits were being weighed to check for injuries or new behavioral issues, such as apprehension or vocalization when being touched. Feed intake was also reviewed. Our facility has successfully housed seven pairs of training rabbits, and another five pairs are currently being acclimated. In almost all instances, the pairings have resulted in an obvious bond between the rabbits. While working to pair house adult female rabbits can be a stressful activity, especially if they are intact females who are unaccustomed to sharing their space with another female, the benefits of a successful pairing far outweigh the negatives. In many facilities, rabbits in training colonies receive little attention outside of regular procedures. Having a cage mate serves as the ultimate form of enrichment for such a social animal. Pair housing ensures the rabbitsreceive some form of exercise, as they seem to enjoy chasing each other. Also, social grooming can help alleviate stress and keep the cage-bound animal clean. Many technicians have reported that they have observed no negative impact on the rabbits' behavior from the pair housing, which means that pair housing may not negatively influence testing or practice procedures.There are many benefits to the employees who work with the pair housed rabbits, as well. They are able to see the animals interact and show behavioral characteristics that singly housed rabbits do not exhibit. Employees also receive peace of mind from knowing that these rabbits are appreciated and that efforts are being made to help them be as comfortable as possible while they are in the facility.