A 6 year old male Scottish Terrier was admitted to Stange Memorial Clinic April 13, 1948, with a history of depression and difficult defecation. For the past 3 weeks small amounts of hemorrhagic feces had been excreted. The patient had suffered a fractured pelvis at the age of 2, and the resulting exostosis had reduced the internal diameter of the pelvis to approximately 11/2 in. A radiograph demonstrated several large masses in the cecum, colon, and rectum. The largest mass, about 6 cm. in diameter, was located in the posterior colon, and 2 masses, each about 2 cm. in diameter were lodged in the cecum.