Intrapericardial Encephalitozoon pogonae–associated arteritis with fatal hemopericardium in two juvenile central bearded dragons

Two male juvenile central bearded dragons (Pogona vitticeps) were submitted for postmortem examination after dying at their respective homes. Dragon 1 had marked hemopericardium with restrictive epicarditis. The inner aspect of the distended pericardial sac was lined by a fibrinoheterophilic membrane. In addition, granulomas abutted the testes. Dragon 2 had acute hemopericardium and granulomatous arteritis of the great vessels exiting the heart. Histologically, both animals had granulomatous arteritis of the large arteries with intrahistiocytic gram-positive, slightly elongated, up to 2 μm long microorganisms that contained a vacuole. These microorganisms were also present in the paratesticular granulomas. On transmission electron microscopy, the microorganisms were identified as microsporidians given the presence of exospore, endospore, vacuole, nucleus, and a filament with 4–6 coils. The microsporidia were identified as Encephalitozoon pogonae based on sequencing of the internal transcribed spacer 1 of the ribosomal RNA genes. Microsporidia are agents of disease in bearded dragons. Intrapericardial arteritis of large arteries with hemopericardium or restrictive epicarditis is a fatal manifestation of this infection.