A retrospective study of the prevalence of amyloidosis in mice from se
veral facilities was done. Amyloid deposition is an age-related lesion
. The influence of common laboratory factors on the occurrence of this
lesion was analyzed. This study documented genotypic difference in su
sceptibility to amyloidosis and showed that caging and pathogen status
both impact on the number of cases of amyloidosis seen in a populatio
n. The lowest percentage of affected mice was seen when the animals we
re individually caged in a specific pathogen-free facility where condi
tions of stress were minimized.