Metastatic renal adenocarcinoma in a mule

A 15-year-old mare mule was presented with a 2-month history of weight loss, lethargy, and anorexia. Clinicopathologic abnormalities were consistent with liver disease. Repeated urinalysis revealed hyposthenuria, but water intake and a water deprivation test were normal, suggesting adequate renal function. Ultrasonography revealed pulmonary, hepatic, and renal masses. Cytologic and histologic examination of pulmonary aspirates and hepatic biopsies, respectively, revealed polygonal neoplastic cells with many mitotic figures, the cells having the characteristics of adenocarcinoma. Necropsy confirmed a primary renal adenocarcinoma with metastasis to liver, lung, lymph nodes and the opposite kidney.