Studies by pancreatography of ductal changes induced by administration of pancreatic carcinogen in two dogs.

To assess the temporal changes of the pancreatic duct following the administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in two dogs, serial pancreatography was performed. They received intraductal administration of a total of 595 and 500 mg ENNG in each one, over the periods of 12 and 13.5 months, respectively. In one dog, sequential changes of the main duct were observed, a small round filling defect developed a circumferential defect and became a severe stenosis associated with proximal dilatation of the duct. While no gross tumors were macroscopically detected at autopsy, continuous lesions with features of hyperplasia, atypical hyperplasia, and cancerous change of duct epithelial cells were microscopically seen. In the other one, a small round filling defect was detected by pancreatography, which was histopathologically hyperplasia of pancreatic duct, rather than cancerous cells. The present dog model for induction of pancreatic duct carcinomas appears useful for elucidating clinico-pathological changes occurring during cancer development.