Kindly provided by Mark Stidworthy of International Zoo Veterinary Group



33 year old adult male captive Western lowland gorilla (Gorilla g. gorilla) in a U.K. zoo. Previously in good health. Vomiting and mild diarrhoea noted in the enclosure overnight. Found lying conscious on back one morning. Appeared to be retching then rapid respiratory arrest. Died.

Describe the gross lesions.

Name the disease.

What were the histologic features of this lesion?

List some additional findings common in such animals.

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Describe the gross lesions
Within the left ventricular free wall and interventricular septum, there are multifocal to coalescent areas of white fibrous tissue dissecting within the myocardium. Changes are most severe in the interventricular septum.

Name the disease

Fibrosing cardiomyopathy

What were the histologic features of this lesion?

Extensive replacement of normal myocardium by coalescent sheets of mature fibrous tissue, interspersed with islands of mature adipocytes. Fibrous tissue is intermingled with slender fibrocytes and blood vessels, with minimal numbers of lymphocytes in some places. Remaining myocardial fibres are disorderly in their arrangement and exhibit pronounced anisocytosis and anisokaryosis, with frequent markedly enlarged hyperchromatic nuclei. Fibres are occasionally necrotic with infiltrating macrophages. Small amounts of fibre lipofuscin are present.

List some additional findings common in such animals.

Additional histological findings that are common in such cases were also present in this animal, including evidence of chronic pulmonary congestion, hepatic and splenic haemosiderosis, renal fibrosis, cardiac lipofuscinosis and adrenocortical nodular hyperplasia.

Briefly discuss the significance and proposed aetiology of this condition.

Fibrosing cardiomyopathy is recognised to be an important disease of captive Western lowland gorillas. This case is typical of those previously described, occurring in a male, middle aged animal, associated with sudden death.

The aetiology of the fibrosing cardiac lesions remains uncertain. Proposed aetiologies include viral infections, vitamin E/selenium deficiency, hypertension, arteriosclerosis, obesity, stress and other infectious and toxic agents. The major study of this condition in gorillas did not identify or fully investigate the aetiology in most of the described cases.

Schulman FY, Farb, A Virmani R, Montali RJ (1995) Fibrosing cardiomyopathy in captive western lowland gorillas (Gorilla gorilla gorilla) in the United States: A retrospective study. J Zoo and Wild Med 26:43-51 [/expand]