title: Markers for heightened monitoring, imminent death, and euthanasia in aged inbred mice.
abstract: The goal of this study was to identify objective criteria that would reliably predict spontaneous death in aged inbred mice. We evaluated male and female AKR/J mice, which die at a relatively young age due to the development of lymphoma, as well as male C57BL/6J and BALB/cByJ mice.  Mice were implanted subcutaneously with an identification chip that also allowed remote measurement of body temperature. Temperatures and body weights were measured weekly until spontaneous death occurred or until euthanasia was performed for humane reasons. In AKR/J mice, hypothermia and  weight loss began about 4 wk prior to death and increased gradually during that antemortem interval. In C57BL/6J and BALB/cByJ mice, these declines began earlier and were more prolonged prior to death. However, C57BL/6J and BALB/cByJ mice developed a relatively precipitous hypothermia during  the 2 wk prior to death. For all 3 strains, the derived composite score of temperature × weight, expressed as a percentage of stable values for each mouse, was similarly informative. These changes in individual and composite measures can signal the need for closer observation or euthanasia  of individual mice. Validated markers of clinical decline or imminent death can allow the use of endpoints that reduce terminal distress, do not significantly affect longevity or survival data, and permit timely collection of biologic samples.
authors: Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, Illinois, USA.
authors: Rita A
authors: RA
authors: Trammell
authors: Lisa
authors: L
authors: Cox
authors: Linda A
authors: LA
authors: Toth
mesh_terms: D000375:Aging / Q000473:pathology*; D000818:Animals; D015415:Biomarkers; D003643:Death; D028601:Euthanasia, Active; D005260:Female; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL
chemical_list: D015415:Biomarkers