Primary colonic hemangiosarcoma in a dog.

A 13-year-old spayed female miniature dachshund dog was presented with a history of hematochezia, melena, and weight loss. A colonic mass detected by exploratory celiotomy was resected and diagnosed as hemangiosarcoma (HSA). Liver lobectomy for hepatic HSA was performed 894 days after surgery. Adjuvant chemotherapy was declined. This is the first documentation of a canine colonic HSA.