Neubauer, T. L., Zabriskie, R., Buckmaster, C. A. 2009. Decline in aggression in cotton rats through the use of enrichment. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 609 (Abstract #P157).

The cotton rat (Sigmodon hispidus) presents a unique susceptibility towards human pathogens and is currently used in studies of human respiratory syncytial virus, adenovirus, and parainfluenza virus. Though valuable, this animal model has earned a challenging reputation with husbandry, veterinary, and research personnel. Cotton rats tend to be hyperactive and aggressive in the lab setting and are likely to leap from their cages or bite when handled. Frequent fighting between cage mates, particularly males, is often brutal and deadly, compromising study results. Our researchers were concerned about the aggression and fighting in their colony and asked for a solution. An Internet search revealed nothing helpful, so we suggested the addition of cardboard tubes (3.2 in. × 5 in. × 0.30 in.) to the cages for shelter and enrichment. We pair-housed the animals and provided 1 tube per male to prevent competition. The change in the animals’ behavior has been overwhelming and our technicians, veterinarians, and researchers are satisfied with the outcome. Prior to the addition of the tubes, it was necessary to handle the rats wearing heavy leather or ISEA level 5 gloves for protection from biting. We now wear latex gloves during cage changing with no more fear of biting than from other common rodents. In 1 y, fight wounds in our cotton rats have decreased by nearly 400% and the animals are typically seen resting peacefully with their cage mates in or near their tubes.