Mesothelioma in cattle: two case reports

Introduction: Mesotheliomas are tumours of the mesothelial covering cells of the serous membranes and their supporting connective tissue of mesodermal origin. In domestic animals, little is known about the pathogenesis or the causative factors of malignant mesothelioma. In people, malignant pleural mesothelioma is associated with asbestos exposure. At present, the available data on the prevalence of mesothelioma in cattle are inconsistent. Aim: This manuscript describes two cases of malignant mesothelioma, one in a cow and one in a young calf. Materials and methods: A 4-year-old Friesian cow with diarrheal syndrome, marked abdominal distension and partial anorexia and a 37-day-old male mixed breed calf with a history of progressive swelling of the scrotum and abdominal distension were examined. Result and discussion: Physical examination enabled to include mesothelioma in the differential diagnosis. Ultrasonography and even more histopathology were decisive for the final diagnosis. The animals were euthanized due to poor prognosis. In both animals, necropsy showed abdominal sero-haemorragic effusion and the presence of firm nodules on the peritoneal surfaces, which extended to the thoracic cavity in the cow and to tunica vaginalis in the calf. Based on gross pathology and histopathologic findings, the adult cow was diagnosed with acquired malignant mesothelioma, while the calf was diagnosed with predominantly epithelioid congenital malignant mesothelioma. Conclusion: Interest in mesothelioma has increased since the association between exposure to asbestos fibres and mesotheliomas has been demonstrated in humans. The four-year-old cow object of this report was stabled in a farm with asbestos roofs. The same situation was not observed in the calf. In respect to the latter, the mesothelioma was considered to be congenital in origin. To the best of our knowledge, the calf presented in this report is the first case of bovine congenital mesothelioma involving tunica vaginalis.