Idiopathic Myocardial Fibrosis in Captive Chimpanzees (Pan troglodytes)

Abstract

Cardiovascular disorders and predominantly idiopathic myocardial fibrosis are frequently associated with mortality among zoo-housed chimpanzees ( Pan troglodytes). Formalin-fixed whole hearts of deceased chimpanzees housed in zoos ( n = 33) and an African sanctuary ( n = 2) underwent detailed macroscopic and histopathologic examination using a standardized protocol. Archived histological slides from the hearts of 23 additional African sanctuary-housed chimpanzees were also examined. Myocardial fibrosis (MF) was identified in 30 of 33 (91%) of the zoo-housed chimpanzees but none of the 25 sanctuary-housed chimpanzees. MF was shown to be characterized by both interstitial and replacement fibrosis. Immunophenotyping demonstrated that the fibrotic lesions were accompanied by the increased presence of macrophages, alpha smooth muscle actin-positive myofibroblasts, and a minimal to mild T-cell-dominant leukocyte infiltration. There was no convincing evidence of cardiotropic viral infection or suggestion that diabetes mellitus or vitamin E or selenium deficiency were associated with the presence of the lesion. However, serum vitamin D concentrations among zoo-housed chimpanzees were found to be lower in seasons of low ultraviolet light levels.

Vitamin D status in chimpanzees in human care: a Europe wide study

“…It is possible that vitamin D de ciency is a signi cant risk factor for cardiac disease in zoo-housed chimpanzees as macrophage-mediated brosis has been shown to induce differentiation of cardiac stromal cells into myo broblasts [53][54][55] . A brosis-associated increase of macrophages and myo broblasts was also shown in a previous study in chimpanzees 11 . Considering the results of this study, together with the high prevalence of idiopathic myocardial brosis (IMF) in chimpanzees 11 , a relationship between vitamin D status and cardiovascular disease seems plausible.…”

A review of research in primate sanctuaries

“…A wide range of clinical conditions specific to primates have thus been studied in sanctuary settings. Cardiac function [198] and disease [199,200] have been investigated in both chimpanzees and bonobos, as well as improvements to cardiac monitoring [201] and heart rate responses to anaesthetic protocols [202]. At Kumamoto, clinical cases of maxillary sarcoma [203], leprosy [204] and Down syndrome [205] have all been reported in chimpanzees, while researchers have also investigated a non-invasive test for tuberculosis in PASA sanctuaries [206].…”

A 25-Year Retrospective Review of Mortality in Chimpanzees (Pan troglodytes) in Accredited U.S. Zoos from a Management and Welfare Perspective

“…The lack of sex differences for intrinsic and extrinsic etiologies in this study is especially noteworthy in regard to cardiac-related deaths, which made up 47% of female deaths and 51% of male deaths in this study sample. Strong et al [ 72 ] also reported a similar finding of males and females being affected by cardiac disease (specifically idiopathic myocardial fibrosis) at similar frequencies. This is in contrast to previous findings, which suggested a much more prevalent link between cardiac issues and sex, with males being much more affected [ 73 ].…”