Neurotuberculosis in cattle in southern Brazil.

Tuberculosis in cattle is a chronic infectious-contagious disease characterized by the development of nodular lesions (granulomas) in mainly the lungs and regional lymph nodes. It is caused by Mycobacterium tuberculosis complex, an acid-fast bacillus (AFB). Tuberculosis in the central nervous system is a rare condition in cattle. Herein, we describe the clinical and pathological findings of six neurotuberculosis cases in cattle diagnosed in Southern Brazil. The average age of the cattle affected was 12 months, and they varied in breed and sex. The clinical history ranged from 5 to 30 days and was characterized by motor incoordination, opisthotonus, blindness, and progression to recumbency. The cattle were euthanized, and grossly, the leptomeninges at the basilar brain showed marked and diffuse expansion, with nodular yellowish lesions ranging in size. On microscopic examination, there were multifocal granulomas located mainly in the meninges, though sometimes extending to adjacent neuropil or existing as isolated granulomas in neuropil. AFBs were observed in the cytoplasm of epithelioid macrophages and multinucleated giant cells through Ziehl-Neelsen histochemical staining and identified as Mycobacterium sp. through immunohistochemistry.