Environmental Enrichment of Laboratory Rodents:
The Answer Depends on the Question
Toth, Linda A.
Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois
Department of Health and Human Physiology, The University of Iowa, Iowa City, Iowa
Thermal Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
Musch, Timothy I.
Departments of Kinesiology, Anatomy & Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
Comparative Medicine, Volume 61
Number 4 • August • Pages 314-321
Efforts to refine the care and use of animals in research have been ongoing for many years and have led to general standardization of rodent models, particularly with regard to animal housing, genetics, and health status. Concurrently, numerous informal practices and recommendations have
been promulgated with the laudable intent of promoting general animal well-being through so-called enrichment of the cage environment. However, the variety of housing conditions fostered by efforts at environmental enrichment (EE) complicates the goal of establishing standardized or even defined environments for laboratory rodents. Many studies over the years have sought to determine whether or how various enrichment strategies affect the behavior and physiology of laboratory rodents. The findings, conclusions, and interpretations of these studies are mixed, particularly with regard to their application across rodent
species, strains, genders, and ages; whether or how they affect the animals and the science; and, in some cases, whether the effects are positive, negative, or neutral in terms of animal well-being. Crucial issues related to the application of EE in research settings include its poorly defined effect on the animals, the potential for increased variability in the data, poor definition across labs and in publications, and potential for animal or scientific harm. The complexities, uncertainties, interpretational conundrums, varying conclusions, and lack of consensus in the EE literature warrant careful assessment of the benefits and liabilities associated with implementing such interventions. Reliance on evidence, professional judgment, and performance standards are crucial in the development of EE strategies.