Spontaneous tumors in domestic hamsters.

A total of 90 tumors from 85 domestic hamsters (70 Djungarian hamsters and 15 Syrian hamsters) were examined by histology. In the Djungarian hamsters, 64 neoplastic and 11 non-neoplastic lesions were identified, whereas 14 Syrian hamsters showed neoplastic disease, and one showed non-neoplastic disease. The Djungarian hamsters showed a high prevalence of neoplastic disease, similarly to laboratory Djungarian hamsters. In the Djungarian hamsters, almost all tumors were integumental, whereas hematopoietic tumors were the most common type in the Syrian hamsters. The most common integumental tumors in the Djungarian hamsters were mammary tumors, atypical fibromas and papillomas, and a spectrum of integumental tumors that have not been reported in laboratory Djungarian hamsters were identified. Most mammary tumors occurred in the females, whereas all atypical fibromas were observed in the males. In the Syrian hamsters, plasmacytomas and lymphomas were the most common tumors. The small number of Syrian hamsters in this study may reflect the low prevalence of spontaneous tumors seen in laboratory Syrian hamsters. The mean age of the affected hamsters was 19.8 months, which is relatively advanced. To our knowledge, this is the first comprehensive study of tumors in domestic hamsters.