"Buck", a 9 year old male castrated Belgian Shepherd Dog, presented to the triage service at Cornell on 9/6/06 after a 3 week history of dysuria and a one day history of vomiting and inappetence. On physical exam at Cornell, Buck was found to have an enlarged and firm urinary bladder and a thick, engorged penis. He was unable to urinate. Diagnostics performed to address Buck's problems included complete bloodwork and urine analysis, contrast urethrography, abdominal ultrasound, penile radiographs, and penile ultrasound. Penile ultrasound showed a fracture of the os penis along with a heteroechoic mass within the penile parenchyma. No evidence of metastatic disease was found on thoracic radiographs or abdominal ultrasound. A penile amputation and scrotal urethrostomy were performed. The mass was diagnosed as a hemangiosarcoma arising from the soft tissue of the penis. Following surgery, Buck was treated with a full course of single-agent doxorubicin chemotherapy. Five months after the surgery, Buck showed no evidence of disease. This paper addresses the diagnostics performed in this case and the therapy initiated to ameliorate Buck?s condition.