INTRODUCTION
Apart from the many inbred strains, substrains, spontaneous mutants, and outbred stocks of laboratory mice, the mouse has been, and continues to be, central to molecular genomics, with worldwide efforts continuing to “knock out” every functional gene in the mouse genome and define the relationship between genotype and phenotype.
In addition to understanding the genome, various mouse strains and stocks, as well as the genetically engineered mouse (GEM), play critical roles in hypothesis-driven biomedical research. These trends have created rich opportunities and critical demand for comparative pathologists who are knowledgeable in mouse pathobiology. Unfortunately, the scientific literature is replete with erroneous interpretation of phenotype by scientists (as well as pathologists) lacking expertise in mouse pathology. Effective mouse pathology requires a global understanding of mouse biology, euphemistically termed ''Muromics" (see Barthold 2002).It is impossible for the pathologist to command indepth knowledge of all strains, stocks, and mutant types of mice, and in many cases there is little baseline data to draw upon. Nevertheless, the mouse pathologist must be cognizant of general patterns of mouse pathology, as well as strain- and GEM-specific nuances. Recommended references (Frith & Ward, 1988; Maronpot et al. 1999; McInnes 2012; Mohr 2001; Mohr et al. 1996; Ward et al. 2000) provide thorough pictorial coverage of spontaneous mouse pathology in several common inbred strains of mice. The incidence and prevalence of strain-specific pathology are highly dependent upon genetic and environmental influences, including diet, bedding, infectious disease, age, sex, and other factors. Compared to the above-cited references, our coverage of the esoterica of spontaneous mouse pathology is relatively superficial.
We herein emphasize general patterns of disease, while attempting to address important strain-, mutant-, and GEM-specific diseases when appropriate. There are a growing number of internet-accessible resources for mouse phenotyping and pathology of strains, stocks, and GEMs.
A listing of these web resources is available through various sources (Bolon 2006; Brayton 2013; Fox et al. 2007, 2015). Although not specifically listed in this text, it is worth “surfing" through these cited websites that provide a plethora of information at multiple levels.The unique qualities of the laboratory mouse and the precision of mouse-related research make infectious agents, even those with minimal (or no) pathogenicity, major concerns due to their potential and sometimes significant impact upon research reproducibility, including phenotype. A challenge that is unique to the mouse is the difficulty in drawing the line between commen- salistic, opportunistic, or overtly pathogenic microorganisms. Since the last edition, a wide variety of immune-deficient GEMs have been created, thereby raising the status of several relatively innocuous infectious agents to the level of pathogens. Immune-deficient mice and new molecular methods of detection continue to reveal previously unrecognized mouse “pathogens," such as a number of Helicobacter spp., norovirus, and most recently, astrovirus. Furthermore, the unrestricted traffic of GEMs among institutions and the pressure to reduce costs of maintenance at the expense of quality control have resulted in the re-emergence of several infectious agents that have not been seen in several decades. We, therefore, unabashedly emphasize mouse infectious diseases in this chapter. Despite advances in husbandry and diagnostic surveillance, we are reluctant to discard entities that may seem to have disappeared from laboratory mouse populations because of their likelihood of return.
Pathology of Laboratory Rodents and Rabbits, Fourth Edition. Stephen W. Barthold, Stephen M. Griffey, and Dean H. Percy. © 2016 John Wiley & Sons, Inc. Published 2016 by John Wiley & Sons, Inc.