Online Issues

Journal Vol 47 (4)

Introduction

The Art and Science of Introducing Animals to the Research Environment

Jeffrey I. Everitt and Steven J. Schapiro

Jeffrey I. Everitt, D.V.M., is Director, Comparative Biology & Medicine, GlaxoSmithKline Research & Development, Research Triangle Park, NC. Steven J. Schapiro, Ph.D., is Associate Professor of Comparative Medicine at The Michale E. Keeling Center for Comparative Medicine and Research, Department of Veterinary Sciences, The University of Texas M.D. Anderson Cancer Center, Bastrop, TX.

Address inquiries or reprint requests to Dr. Everitt, GlaxoSmithKline Research & Development, P.O. Box 13398, Five Moore Drive, Research Triangle Park, NC, or email jeffrey.x.everitt@gsk.com.

Key Words: animal acclimation; animal preparation; metabolism study

Every animal care and use program, regardless of the type of research supported or the species utilized, must implement processes to prepare animals for the laboratory environment. In the Guide for the Care and Use of Laboratory Animals (NRC 1996), it is stated that newly received animals should be given a period for physiologic, psychologic, and nutritional stabilization before use. Despite the general consensus of agreement within the laboratory animal science community regarding the necessity of this provision, there is relatively little in the literature to guide the process for developing best practices in this area. The art of common sense and professional judgment are often applied, albeit sometimes not as frequently as should be when data-driven science is lacking. In this age of ever greater sharing of unsupported assertions and thoughts through LISTSERVES and other forms of nonreviewed electronic means, it is imperative for the animal care and use community to use fact-based knowledge whenever and wherever possible to develop institutional best practices and guidelines.

Both art and science are involved in the way animals are prepared for the research environment, and much can be learned from colleagues in other animal science endeavors. The principles that govern how we prepare laboratory animal species for the research environment are not all that dissimilar from principles of preparing livestock for housing and use. The interested reader is encouraged to examine the published works of the noted veterinarian Temple Grandin, who has written extensively on how to prepare livestock for handling and use. It has been shown that for cattle, the interplay of genetic factors affecting behavior, as well as previous experience, strongly determines fear responses during handling (Grandin 1997). Dr. Grandin stresses the need for understanding species-specific behaviors, the need for designing appropriate equipment, and perhaps most importantly, the need for training personnel in how animals are best handled (Grandin 1993). She discusses the utility of training animals when appropriate to voluntarily cooperate with veterinary procedures, and the importance of assessing both behavioral and physiological measurements for adverse effects on animals (Grandin 1999). These issues of livestock handling do not differ from those we face in the laboratory animal science arena.

The preparation of animals for experimentation involves all facets of the animal care and use community including animal breeders and vendors, those who prepare and transport animals, those involved with institutional animal care and use programs, as well as the research community that utilizes animals and analyzes data from in vivo experiments. All too often the researcher who orders an animal from a catalog thinks that the start of the in vivo study is the start of his or her experimental protocol, rather than also considering how that animal has been prepared for entry into the institutional animal care and use program, facility, and/or experimental setup. Laboratory animal veterinarians may think solely of microbial factors and disease prevention issues when designing methods to prepare animals for the laboratory, without giving thought to experimental endpoints. For instance, in some facilities the preparation period for nonhuman primates may be designed to allow for three negative tuberculosis examinations with the minimum 2-wk period between them, but this time may not be enough to allow animals to acclimate for some commonly assessed physiologic parameters (Hassimoto et al. 2004).

The lack of awareness of how animals need to be habituated to novel environments can lead to serious effects on experimental data. It has been shown for instance that acclimation of rats to metabolism cages for 21 days led to a 60-fold reduction in median lethal dose (LD₅₀) responses to a nephrotoxic substance compared with the same study in nonacclimated animals (Damon et al. 1986). This response was shown to be due to the fact that nonacclimated animals were not accustomed to drinking in the novel housing environment and that the dehydration augmented nephrotoxicity. The use of metabolism cages is not uncommon and can provide a source of stress for rats (Eriksson et al. 2004). One can imagine that with increasingly sensitive and multiplexed endpoints such as those of metabonomic and metabolomic studies, it becomes even more critically important to assess and understand acclimation requirements (Nicholls et al. 2003). It has been shown that the design of acclimation schemes for metabolism caging must take into account differences in the influence of age on the stress response (Gil et al. 1999). Thus optimal preparation methods for research animals may require customization based on experimental design and endpoints.

As scientists utilize increasingly sophisticated technologies in research animals, such as telemetric monitoring and noninvasive functional imaging techniques, the need for data-driven acclimation methods becomes obvious. Studies have shown that procedures for the minimization of stress are useful for enhancing the quality of data in functional magnetic resonance imaging in conscious animals, a method that is establishing itself as a critical tool for neuroscientists and scientists in other disciplines (King et al. 2005). While control of the research environment may pose challenges to modern methodology, these methods also provide great opportunity. Methods such as telemetric monitoring should allow laboratory animal scientists the means with which to develop the data necessary to better optimize how animals are prepared for the research environment. These data are needed because there are many gaps in our knowledge concerning adaptation periods for stabilization of physiological parameters (Linden and McEachern 1985).

This issue of ILAR Journal brings together articles written by an experienced group of laboratory animal scientists of diverse backgrounds, who work across a wide range of species, to discuss the topic of animal preparation for the research environment. Despite the diversity of the species discussed (ranging from mouse to chimpanzee), there are many similarities in approaches to animal preparation, and although methods might differ in importance depending on the species, the goals remain the same. Those goals are to minimize adverse effects on animals consistent with good animal welfare as well as to reduce variation in experimental data due to uncontrolled causes.

We hope that this ILAR Journal issue will provide insight into the design of institutional processes and be useful to animal care and use programs. More importantly, we hope that it provides a stimulus and encouragement for laboratory animal scientists to acquire and publish data that promote the refinement of methods and guidelines in this area.

References

Damon EG, Eidson AF, Hobbs CH, Hahn FF. 1986. Effect of acclimation to caging on nephrotoxic response of rats to uranium. Lab Anim Sci 36:24-27.

Eriksson E, Royo R, Lyberg K, Carlsson H-E, Hau J. 2004. Effect of metabolic cage housing on immunoglobulin A and corticosterone excretion in faeces and urine of young male rats. Exp Physiol 89:427-433.

Gil MC, Aguirre JA, Lemoine AP, Segura ET, Barontini M, Armando I. 1999. Influence of age on stress responses to metabolic cage housing in rats. Cell Mol Neurobiol 19:625-633.

Grandin T. 1993. Teaching principles of behavior and equipment design for handling livestock. J Anim Sci 71:1065-1070.

Grandin T. 1997. Assessment of stress during handling and transport. J Anim Sci 75:249-257.

Grandin T. 1999. Safe handling of large animals. Occup Med 14:195-212.

Hassimoto M, Harada T, Harada T. 2004. Changes in hematology, biochemical values, and restraint ECG of rhesus monkeys (Macaca mulatta) following 6-month laboratory acclimation. J Med Primatol 33:175-186.

King JA, Garelick TS, Brevard ME, Chen W, Messenger TL, Duong TQ, Ferris CF. 2005. Procedure for minimizing stress for fMRI studies in conscious rats. J Neurosci Methods 148:154-160.

Linden W, McEachern HM. 1985. A review of physiological prestress adaptation: Effects of duration and context. Int J Psychophysiol 2:239-245.

Nicholls AW, Mortishire-Smith RJ, Nicholson JK. 2003. NMR spectroscopic-based metabonomic studies of urinary metabolite variation in acclimatizing germ-free rats. Chem Res Toxicol 16:1395-1404.

NRC [National Research Council]. 1996. Guide for the Care and Use of Laboratory Animals. 7th ed. Washington DC: National Academy Press.