Resumo:
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.
