Chronic liver disease in cattle associated with ingestion of Brachiaria spp.

ABSTRACT: One hundred and ninety livers condemned due to chronic disease (fibrosis) were evaluated in a bovine slaughterhouse over 12 months. Hepatic lymph nodes were also examined while still attached to livers. The major macroscopic lesion observed in the livers was moderate to severe atrophy of the left lobe associated with compensatory hypertrophy of the right lobe. Histologically, the main changes corresponded to sites of macroscopic lesions, and fibrosis was observed in all livers, along with bile duct hyperplasia and neovascularization. Masson's trichrome stain highlighted the fibrous connective tissue. Most of the livers analyzed had macrophages with foamy cytoplasm and a peripheral nucleus that infiltrated fibrotic areas. Immunohistochemistry (IHC) for macrophages with monoclonal antibody clone MAC 387 revealed that the cytoplasm of the foamy macrophages of the liver and of the hepatic lymph nodes were positively immunostained. These cells are frequently associated to the consumption of grasses of the genus Brachiaria. Although the liver gross lesions described in this study have not been previously reported in animals consuming Brachiaria , the associated changes observed histologically, such as fibrosis and infiltration of foamy macrophages, showed a new form of chronic liver disease probably associated with the consumption of this forage. The IHC technique was important to prove that the foam cells observed are macrophages.