Caracterização epidemiológica, clínica e patológica de uma doença que cursa com edema crônico em bovinos no estado da Bahia

Abstract

For almost 30 years, a disease of unknown etiology, characterized by severe chronic subcutaneous edema, has been affecting cattle in the North-Central and South-Central regions of Bahia State, Brazil. The disease is seasonal and occurs during prolonged dry periods in the summer, resulting in high mortality rates among cattle in the region. This study aimed to investigate the epidemiological, clinical, and pathological characteristics of this disease. Fifteen outbreaks of the disease that occurred between October 2023 and April 2025 in 12 municipalities in Bahia were studied. Clinical examinations were performed on 46 sick animals, from which blood samples were collected for hematological and biochemical tests. Anatomopathological studies were performed on seven animals, and pastures were evaluated on all properties studied. Outbreaks occur between October and December, and cattle become ill after two to three months of access to native forest. The disease is characterized by chronic subcutaneous edema, especially in the head, dewlap, thorax, and forelimbs, as well as progressive weight loss, jugular vein distension, dyspnea, cardiac arrhythmia, and death. Laboratory tests indicated anemia and hypoproteinemia due to hypoglobulinemia in some animals, as well as significant elevations in the CK enzyme. The anatomopathological study observed hydropericardium, hydrothorax, ascites, and right ventricular dilation. Histological evaluation revealed marked hypertrophy of smooth muscle cells in the tunica media of the pulmonary arteries and arterioles, sometimes with an eccentric, irregular, and asymmetrical arrangement. It was concluded that the disease occurs as a consequence of right heart failure due to pulmonary arterial hypertension (chronic cor pulmonale), and epidemiological data and inspections of pastures where the affected animals were kept suggest that the cause is a toxic plant.