As the only North American marsupial, opossums are commonly used in educational programs in U.S. zoos and aquariums. Opossums (Didelphis virginiansis) can be trained for a variety of commands; however, with an average lifespan of only 1–2 years in the wild, and 3–4 years in captivity, opossums are not equipped for a long career in our zoological facilities. Anecdotally, opossums as well as other small mammals are known for having a relatively high incidence of heart disease. This exact incidence rate is unknown, and risk factors for heart disease have not been evaluated for this species. At two independent zoo pathology services, the relative prevalence of cardiomyopathy in opossums was determined to be approximately 17%. This is considered high compared to data collected on domestic dogs,1 northern fur seals,2 African hedgehogs,3 and meerkats4. In domestic cats, cardiomyopathy is also common, being found in 16% of healthy cats.5 Taking this into account, it appears that opossums may be similar to cats in overall prevalence of cardiomyopathy. However, while cats predominantly display hypertrophic cardiomyopathy (HCM) with histologic characteristics of concentric ventricular hypertrophy, opossums tend to have degenerative cardiomyopathy being characterized histologically by multifocal degeneration of myocardiocytes, or dilated cardiomyopathy (DCM), similar to the lesion seen in some dog breeds, domestic ferrets, and giant anteaters. This paper will outline the signalment and possible risk factors associated with the high relative incidence of cardiomyopathy in North American opossums. Moreover, we recommend evaluating cardiac function during annual examinations to assist in early diagnosis and potential treatment in this species.
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