Abstract
A 5-year-old female rhesus macaque (Macaca mulatta) suddenly began suffering from anorexia, dysphagia, vomiting, diarrhoea, and anaemia. Clinical examination and conventional radiography were uneventful. Additionally an ultrasound (US) and computed tomography (CT) were performed which revealed a large tumorous mass in the upper abdomen and a lung metastasis. Using sonographic guidance, a biopsy of the abdominal masse was taken. Histopathological analysis revealed the diagnosis of a squamous cell carcinoma. At autopsy, an advanced gastric carcinoma, which originated from the cardia, was found with infiltration of the retroperitoneum, and metastatic involvement of the mesenterial lymph nodes as well as metastasis in the lung parenchyma. This case illustrates the usefulness of modern non-invasive imaging techniques, including US and CT, in enabling a quick and accurate diagnosis in laboratory animals.