To provide up-to-date information on the incidence and risk factors of canine testicular tumors, 476 pathological reports of male canine tumors from two institutes of veterinary medicine in Taiwan over a period of 12 years were reviewed. The detection rate of testicular tumors was 16.8% (80/476) in male canine tumors, and 94.1% (80/85) in male genital tumors. Ninety-six testicular tumors from 80 dogs were identified in this study, including 33 (34.4%) seminomas (SEMs), 25 (26%) interstitial cell tumors (ICTs), 22 (22.9%) mixed germ cell-stromal cell tumors (MGCSCTs), and 16 (16.6%) Sertoli cell tumors (SCTs). Of the 96 testicular tumors, 52 (54.2%) tumors developed from cryptorchid testes in 45 dogs (56.3%), and 44 (45.8%) tumors developed from scrotal testes in 35 dogs (44.7%). Cryptorchidism was significantly associated with development of MGCSCTs, SCTs, and SEMs, but not ICTs (p<0.01). The detection rate of testicular tumors in the dog younger than 10-years-old was significantly associated with cryptorchidism (p<0.01). Except for mixed breed dogs, the Maltese breed had high detection rate of testicular tumors, and may have high risk in cryptorchidism in this study. In conclusion, our results indicate that cryptorchidism alone or in addition to age will significantly affect the incidence and type of canine testicular tumors, and a high detection rate of testicular tumors in Maltese dogs is documented for the first time.

The characteristics of 163 spontaneous neoplasms diagnosed in 150 necropsied zoo mammals, birds, and reptiles at Taipei Zoo during 1994-2003 were analyzed. Histopathology and immunohistochemistry were employed to classify the tumor types. A total of 2657 necropsied zoo animals, including 1335 mammals, 873 birds and 449 reptiles led to the diagnosis of tumor in 8.1% (108/1335), 4.2% (37/873) and 1.1% (5/449) of cases, respectively. The most predominant type of tumors in mammals was mammary gland tumors (12.0%, 13/108), followed by uterine smooth muscle tumors (10.2%, 11/108), lymphosarcoma (9.3%, 10/108), hepatocellular carcinoma (8.3%, 9/108), and cutaneous squamous cell carcinoma (6.5%, 7/108). The avian neoplasm with the highest incidence was lymphosarcoma (35.1%, 13/37). Five individual neoplasms were found in different reptile species. The overall incidence of malignant tumors (63.8%, 104/163) was greater than that of benign tumors (36.2%, 59/163). Immunohistochemistry characterization of these tumors revealed a histogenesis which is similar to that seen in domestic animals and humans.

A 24-year-old, spayed female Malayan sun bear ( Helarctos malayanus) in the Taipei Zoo (Taipei, Taiwan) showed clinical signs of slowly progressive anorexia, dullness, compulsive pacing, and circling. The animal subsequently developed acute severe stupor and persistent recumbency. Postcontrast study of computed tomography revealed a spheroid, extra-axial mass with strong but heterogeneous hyperattenuation in the left temporal lobe of the cerebrum. At necropsy, a solitary, well-circumscribed intracranial mass measuring 3 cm × 2.5 cm × 2 cm was attached to the left pyriform lobe with compression of the adjacent neuroparenchyma. Cytological examination obtained from the mass revealed large clumps and sheets of cohesive polyhedral cells with round nuclei, wispy cytoplasm, and indistinct cell borders. Microscopically, the mass was composed of densely packed round to polygonal cells arranged in lobules and small nests. Psammoma bodies, xanthomatous change, and cholesterol deposition were also noted. Immunohistochemical staining of the tumor was positive for vimentin, pancytokeratin, cytokeratin (CK)34BE12, neuron-specific enolase, and epithelial membrane antigen, but negative for glial fibrillary acidic protein and S100 protein. The cytological, histological, and immunohistochemical features were compatible with a meningothelial meningioma.