UTEROOVARIAN INFECTION IN AGED B6C3F1 MICE

  • 1 April 1987
    • journal article
    • research article
    • Vol. 37  (2) , 153-158
Abstract
An unusually high number of ovarian masses and cysts with purulent material were observed in the B6C3F1 mice on 2 year chemical carcinogenicity studies sponsored by the National Cancer Institute-National Toxicology Program. To determine possible etiology, some of these lesions were cultured for bacteria and a majority yielded Klebsiella sp. Necropsy records of 14,029 female mice in 91 chronic studies necropsied from 1979 to 1983 at six toxicology testing laboratories were reviewed to determine the incidence of lesions and distribution of this disease. Animals for these studies were obtained from barrier production colonies of six suppliers. The incidence of this lesion was low in animals less than 14 months of age, increased with age and reached a peak in 24-26 month old mice. Most animals having this lesion either died or were sacrificed in moribund condition, indicating that this is a life shortening disease of aged B6C3F1 mice. The incidence of lesions ranged from < 1% to 70% in different chronic studies. There was a marked difference in the incidence in mice from different suppliers and the incidence rate was 2.6 to 15% depending on the source of the animals. The incidence of this lesion in some testing laboratories was several-fold higher than in others and ranged from 0.9 to 20%. The proportion of mice with this lesion was low in some laboratories irrespective of the source of the animals, whereas in other laboratories the incidence was several-fold higher with animals from some, but not all suppliers, indicating testing laboratory-supplier interaction. The incidence of lesions in gavage studies was higher than in the feed, inhalation and skin paint studies. A marked decrease in the incidence of this disease was achieved by not using animals from production colonies harboring the organism suspected of causing this lesion and by revising flushing and sanitization procedure for the automated watering manifolds of cate racks in the 2 year studies.

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