Fibrosing Cardiomyopathy in Captive Western Lowland Gorillas (Gorilla gorilla gorilla) in the United States: A Retrospective Study
Fibrosing cardiomyopathy defined as myocardial replacement fibrosis with atrophy and hypertrophy of cardiac myocytes, absent to mild myocardial inflammation, and no apparent etiology or associated disease condition was identified in 11 captive western lowland gorillas (Gorilla gorilla gorilla) in the United States. All 11 were male and ranged from 11 to 37 yr of age (x̄ ± SD = 26 ± 8 yr). In eight cases involving gorillas 16-37 yr of age (x̄ ± SD = 28 ± 7 yr), cardiac scarring was considered fatal. Seven of these eight gorillas died suddenly. Histologically, all eight hearts had multifocal to coalescing, moderate to marked myocardial fibrosis with atrophic and hypertrophied cardiac myocytes. Six gorillas exhibited minimal to mild inflammation, and three had vascular disease. Atherosclerosis was considered contributory in only one case. The deaths of three gorillas with fibrosing cardiomyopathy could not be directly attributed to myocardial fibrosis. Their hearts exhibited similar but less severe myocardial fibrosis than that seen in hearts considered fatally scarred. All three had mild myocardial inflammation, but notable vascular disease was not seen in any gorilla. Fibrosing cardiomyopathy was a significant (P = 0.007) cause of sudden death in adult male gorillas in this study. Additional research is necessary to identify the underlying cause(s) of this syndrome and improve the management of the captive gorilla population.