Causes of Mortality and Profile of Spontaneous Tumors in Young CD-1 Mice

ESVP-ECVP 2022 -- CD-1 mice are the strain of mouse most commonly used for chronic studies in Europe. Knowledge of the profile of spontaneously occurring neoplasms of rodents is essential for differentiating spontaneous and test item-related tumor patterns. The availability of reference material such as historical control data (HCD) with incidences of spontaneous findings is paramount for the pathologist. Comparison of the tumor incidence rates in treated groups with both concurrent control groups and HCD can, along with other study data, help to determine biological relevance in that study. HCD is helpful in interpreting the tumor incidences in a variety of situations, such as: rare tumors, common tumors, tumors with highly variable incidence rates, a tumor that has a marginal increase in incidence relative to concurrent controls, or if there are unexpected increases or decreases of tumor incidences in study control animals (Elmore 2009). Specific information on the incidence of spontaneous neoplastic and non-neoplastic lesions in CD-1 mice during the first year of life is scarce. The aim of this study was to establish the incidence patterns of tumours and major factors contributing to death (MFD) in 1 year control CD-1� mice from Charles River Laboratories based on recent data. In addition, to identify any changes in mortality or tumor incidence patterns over the years, these data were compared with a similar survey by Son et al. in 2004 performed on mouse studies run at Labcorp, Huntingdon (then Huntingdon Life Sciences) between 1990 and 2002.