Edema crônico em bovinos no estado da Bahia

Abstract

For approximately 20 years, outbreaks of a disease of unknown etiology, which courses with chronic subcutaneous edema, especially in the region of the head, dewlap, chest, and forelimbs, have been observed in cattle in the State of Bahia, especially in areas close to the Chapada Diamantina. The objective of this research was to investigate the etiopathogenesis and describe the clinical, epidemiological and anatomopathological data of the disease. We studied 7 outbreaks (A-G) of the disease that occurred between 2007 and 2017, reviewing all medical records, files and archived anatomopathological reports, which were complemented by collecting information from the owners and veterinarians who followed the outbreaks. The histopathological slides were reviewed after making new histological sections. In addition, between 2020 and 2021, five visits were carried out to farms suspected of having the disease to collect information and inspect pastures in search of toxic plants. The disease was characterized by subcutaneous edema, effusions, and right ventricular dilatation, with degeneration and necrosis of cardiomyocytes. There is multifocal marked hypertrophy of the smooth muscle of the middle layer of the arteries and arterioles, sometimes with an eccentric, irregular and asymmetrical disposition. Additionally, there were signs of myocyte proliferation, vacuolization, and disorganization of adventitia cells and periarteriolar fibrosis. The historical and epidemiological data and the inspection of some pastures where the outbreaks occurred, indicated a possible toxic etiology associated with the ingestion of Fridericia cinerea. However, in a pilot experiment in a calf the administration of 40g/kg of F. cinerea for 60 days was not able to reproduce the disease. Although the etiology of the disease remains unknown, outbreaks of “chronic edema disease” in cattle in the State of Bahia are described for the first time. Apparently, the clinical picture characterized by chronic edema is associated with right heart failure secondary to pulmonary arterial hypertension (chronic cor pulmonale). It is suggested that it is a previous unknown disease caused by a toxic plant that induces lung lesions. This disease should be included in the differential diagnoses of other diseases causing chronic edema in cattle.