Genital tract involvements in a bull affected by bovine besnoitiosis

Bovine besnoitiosis is a parasitic disease of cattle caused by the cyst-forming coccidian Besnoitia besnoiti. The parasite targets mainly skin, mucosal membranes, scleral conjunctiva, endothelial cells of large vessels and testes. Severe necrotising inflammation of the latter (orchitis) may result in permanent infertility. The aim of these investigation was to describe the gross and histopathological testicular lesions observed in a 14-months old Limousine bull affected by besnoitiosis. Gross examination of the samples revealed characteristic diffuse scleroderma and hyperkeratosis, especially in scrotal skin. There was diffuse hyperemia of testes and sporadically visible presence of cysts at the level of the testicular coverings and the preputial mucosa. Microscopical observation revealed characteristic cysts of Besnoitia spp. distributed in subcutaneous tissue of scrotum. Many cysts were found also in penis, testicular coverings, testicular tubules, and epididymis. The observed cysts were variable in size from 250 to 300 mu m in diameter, and showed the parasitophorous vacuole containing typical 7.0x2.0 mu m basophilic banana-shaped Besnoitia spp. bradyzoites. A moderate inflammatory response, composed by macrophages, eosinophils and scattered lymphocytes, was seen near and around the cysts. The presence of multiple Besnoitia spp. cysts in different section of the reproductive tract of the bull is confirmed. Moreover, the presence of the cysts in the testicular tubules (parenchyma), epididymis, in the penis may explain the potential impaired fertility of the bulls.