SPONTANEOUS PATHOLOGY OF THE GRAY SHORT-TAILED OPOSSUM (MONODELPHIS-DOMESTICA)

The gray short-tailed opossum, Monodelphis domestica, is a newly estab lished laboratory animal that is becoming increasingly important to bi omedical research. Because little disease information is available for this species, we reviewed records for spontaneous gross and histologi c lesions and microbiologic results in 150 M. domestica necropsies dur ing an 11-year period. We identified 150 (91 female, 59 male) animals from 441 necropsy cases which were controls in experimental protocols or were members of the breeding colony. Initial statistical examinatio ns indicated that the sample was representative of the living members of the breeding colony with respect to age, sex, and range of inbreedi ng. Causes of death and types of tumors were specifically evaluated. F emales died earlier than males (22.6 +/- 13.0 months versus 30.9 +/- 1 1.9 months), but this difference was not associated readily with diet or inbreeding levels. The organ systems with the greatest lesion preva lences, in decreasing order, were the digestive, urogenital, cardiovas cular, and respiratory systems. The most probable causes of all deaths were associated with the digestive system, followed by the cardiovasc ular and integumentary systems. The principal disease problems were re ctal prolapse, congestive heart failure, and dermatitis. Neoplasia was found in 39 of the animals. The prevalence of neoplasia was greatest in the digestive system, followed by the endocrine, urogenital, integu mentary, and hematopoietic systems. Pituitary adenoma was the most com mon neoplasm, followed by uterine leiomyoma and cutaneous lipoma. Spec ific microbially-induced diseases were not recognized, and endo- and e ctoparasites were not found in colony-born M. domestica.