Bronchopulmonary Aspergillosis Associated with Acute Myocardial Infarction in Dog

Abstract

Background: Fungi of the genus Aspergillus are ubiquitous microorganisms of opportunistic character, of which animals and humans are continually exposed. Are described three main forms of aspergillosis in dogs: nasal, disseminated and bronchopulmonary. This form which is restricted to the lung parenchyma is considered rare in dogs. The aim of this paper is to report a case of pulmonary aspergillosis associated to acute myocardial infarction in a dog, focusing on epidemiological, clinical, pathological and immunohistochemical characteristics.
Case: A male dog, 4-year-old, Pinscher, clinically presented dyspnea, anorexia, vomiting, concentrated urine and dark and mollifed faeces. On physical examination, there were congested oral and conjunctival mucosas, dehydration and petechiae in the outer ear. The animal died fve days after the clinical attendance and was sent for necropsy. The macroscopic lesions were restricted to the lung, heart and liver. There were multifocal areas of consolidation in the lung parenchyma and yellowish content in the trachea and bronchi lumen. The heart was rounded and with pale areas in the myocardium. Liver was discreet accentuation of the lobular pattern. Histologically the lesion was characterized by pyogranulomatous and necrotizing bronchopneumonia, multifocal to coalescing, moderate, associated with myriads of intralesional hyphae consistente with Aspergillus spp., associated with acute myocardial infarction. The hyphae weakly stained basophilic by hematoxylin and eosin were strongly impregnated by Grocott’s methenamine silver nitrate and showed strong immunolabelling of the cytoplasm, which were evidenced in brown. There were areas of acute myocardial infarction and hepatocellular degeneration and congestion in the liver, although fungal hyphae were not observed in these tissues.
Discussion: The diagnosis of pulmonary aspergillosis was established based on the morphological and tinctorial characteristics of the agent and confrmed by immunohistochemistry. In this case, is not included in the clinical history any conditions that could promote immunosuppression, neither were observed morphological changes in the pathological examination which suggested other intercurrent diseases. It is likely that the dog has been exposed to the inhalation of large amounts of conidia for a long period of time, condition that favors the occurrence of the disease, even in immunocompetent animals. Probably were not evidenced severe respiratory clinical signs, that characterize the pulmonary impairment, due to the shortcourse of the disease. The pyogranulomatous and necrotizing inflammatory reaction is typical of fungal infection and was restricted to the lung parenchyma. The areas of coagulation necrosis observed in the myocardium are probably secondary to vascular injury caused by the fungi, with subsequent thromboembolism, ischemia and infarction. In Brazil, there are few reports of aspergillosis in dogs, have been reported the nasal and systemic forms. In the world literature, there are few reports about this bronchopulmonary form of the disease. Although uncommon, pulmonary aspergillosis should be considered in the differential diagnosis of diseases that affect the lower respiratory tract of dogs, as well as it’s systemic complications resulting from angioinvasive characteristic of the fungus, which in this case was determinant to the death of the animal.

Keywords: Aspergillus, fungal disease, respiratory tract