Adenocarcinomas of the stomach induced in beagle dogs by oral administration of N-ethyl-N'-nitro-N-nitrosoguanidine.

Two 8-month-old and two 4-month-old male beagle dogs received 250 ml of 150 microgram/ml solution of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) and 2% Tween 60 mixed with a pellet diet twice a day for 8 months as the same methods used for mongrel dogs in our first report [Juntendo Medical Jouranl 19, 579-583 (1973)]. Gastric carcinomas with distant lymph nodes metastases occurred in three beagle dogs except for one died from anesthesia at the endoscopy. Metastases to the liver were observed in two beagles. In the most long-lived beagles, peritonitis carcinomatosa with ascites and metastases to the liver, lungs, bones, and skin were found. Main gastric tumors were located at the subcardia in two dogs (elevated tumor in dog No. 6, ulcerated tumor in dog No. 8), but in dog No 7 at the angulus (ulcerated tumor). Histologically, carcinomas were composed of poorly differentiated adenocarcinoma, signet-ring cell carcinoma, tubular adenocarcinoma, and undifferentiated adenocarcinoma. In all of three dogs which developed adenocarcinoma of the stomach, Stewart's criteria were completely satisifed. Using our methods the target organ is limited only to the stomach, without any sarcomatous lesion of the intestines.