Intoxicação experimental por Ramaria flavobrunnescens em bovinos: estudo da patogenia

Abstract

This study way carried out to determine the pathogenesis of the lesions obseved in the hooves, tongue and stem (tail) of cattle poisoned by Ramaria flavo-brunnescens. The mushroom was collected daily between March and May 2004, immediately liquefied with water and gived to three Jersey calves aged 9-10 months. Daily doses were approximately 20g/kg of body weight during 7 (1 calf) on 13 days (2 calves), aditionly the calves were fed with concentrated commercial ration, water, and native pasture. The total doses of mushroom given were 140, 268, and 261g/kg of body weight. One caft with same age and breed was used as control. Clinical signs were characterized by anorexia, hyperemia of oral mucosa, hypersensibility of the hooves and loosening of the long hairs of tail. The experimental calves were euthanatized and necropsied on days 8 (1 calf) and 15 (2 calves) after the beginning of the experiment. Microscopic lesions were characterized by smoothness of dorsal epithelium of the tongue with loss the tip of filiform papillae and vacuolation of keratinocytes. There was vacuolation and irregular keratinization in the laminar epidermis and hyperplasia of keratinocytes. In the skin of tail hyperkeratosis, vacuolation of the external root sheath and inflammatory infiltration around hair follicles. Were observea Immunohistochemical results with anti-cytoceratin and anti-Ki67 (Mib-1) antibodies demonstrated no differences between the dorsal epithelium of the tongue of control and experimental calves. Ultrastructural study demonstrated decrease in tonofilaments and increase intercellular spaces.