144 An Australian shepherd dog presents with a history of several days of tenesmus, frank blood on the stool, and occasional diarrhea. On rectal examination, a soft tissue mass approximately 2 cm in diameter is readily palpable in the distal rectum; the mass is easy to exteriorize (Figure 144.1). https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9780429401725/fe6fa303-c714-41e4-95cc-94c10c7f2fd1/content/fig144_1_C.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>

i. What tumor types should be on your differential diagnosis list for this dog?

ii. Assuming that this tumor is a benign polyp, what is the likelihood of complete removal?

iii. What anatomical forms of colonic carcinoma are recognized?

iv. How does the prognosis differ for the various forms of colonic carcinoma?