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An observational assessment method for aging laboratory rats
Citation:
PHILLIPS, P., K. JAREMA, D. KURTZ, AND R. C. MACPHAIL. An observational assessment method for aging laboratory rats. LABORATORY ANIMAL SCIENCE. American Association for Laboratory Animal Science, Memphis, TN, 49(6):792-799, (2010).
Impact/Purpose:
The confluence of increasing research into aging, concern over susceptibility to environmental pollution, and attention to the care and well-being of laboratory animals, emphasizes the need for a simple, efficient test to evaluate the health and condition of aging animals.
Description:
The growth of the aging population highlights the need for laboratory animal models to study the basic biological processes ofaging and susceptibility to toxic chemicals and disease. Methods to evaluate health ofaging animals over time are needed, especially efficient methods for large research colonies. This report describes an observational assessment which scores appearance, posture, mobility, and muscle tone on a 5-point scale, which can be completed in about one minute. Tests were applied to male Brown Norway rats between 12 and 36 months of age (n=32). Results demonstrated that aging-related signs ofdeterioration did not appear before 18 months. Assessment scores and variability then increased with age. The rise in total score with age was well described by a 4-parameter logistic function (r=0.967). Body weights increased until approximately 24 months, then remained stable, but decreased after 31 months for the remaining few. The incidence ofdeath increased slightly from 20 to 28 months ofage, and then rose sharply; median survival age was approximately 30 months and the maximum was 36 months. The results of this study provide normative data on aging in male Brown Norway rats. The observational assessment provides an efficient means to monitor the health of aging rats and may be applied to study susceptibility to toxicants, drugs and diseases in old age. Key Words: Aging, Brown Norway, Longevity, Observational Assessment, Rat
