Extraneous variables (2007)

LAREF [Laboratory Animal Refinement and Enrichment Forum]

Abstract

This chapter deals with the following extraneous variables: Exposure to distressed conspecifics; construction noise; researcher; workdays versus weekends/holidays; individually ventilated caging (IVC); restraint tube for rodentsExposure to distressed conspecifics: Being exposed to a distressed conspecific changes the physiological equilibrium of an animal, without the animal necessarily showing this in his/her behavior.Construction noise: Given the fact that noisy construction and remodeling work is a common event in biomedical research facilities, it is surprising that not a single article could be found in the scientific literature, assessing the impact of this uncontrolled variable on animals assigned to research.Researcher: Researchers, who pretend to be too busy to show an active interest in the welfare of the animals assigned to their studies, cannot assure that the data they are collecting will not be influenced by uncontrolled variables related to species-inadequate housing and species-inadequate handling prior, during and after procedures.Workdays versus weekends/holidays: The stress level of animals is higher on workdays as compared to days when no personnel are around. This phenomenon has implications for the interpretation of stress-sensitive data, as these may not reflect normal resting values on ordinary workdays.Individually ventilated caging (IVC): If properly adjusted to the animals' behavioral needs, such as building nests and sleeping in a nest or shelter, and if properly and reliably serviced, an individually ventilated caging system can enhance animal welfare.Restraint tube for rodents: Enforced restraint is not necessarily an intrinsic stressor for rodents. If an animal has been well familiarized with the handling personnel and with the restraint tube, the tube kept dark and the duration of the restraint session kept short enough to forestall overheating, behavioral signs of stress can be avoided. It needs to be demonstrated whether physiological stress parameters reflect baseline values in animals who seem to accept tube-restraint.