Haemangiosarcoma of the <i>os penis</i> in a dog: The most common neoplasm of the canine penis.

A castrated 9-year-old intact male boerboel cross-breed dog was presented with a month-longhistory of stranguria. On physical examination, a mass was noted at the caudal extremity of the os penis. Haematology, serum chemistry and urinalysis were all unremarkable. Abdominal and urethral ultrasound demonstrated an enlarged bladder and a dilated urethra, whichwas followed to the caudal extremity of the os penis. A hyperechoic, roughly spherical,vascularised mass was noted at the caudal os penis, which resulted in obstruction of the penileurethra. Radiographs demonstrated a soft tissue mass with osteolysis of the os penis. Cytologysuggested an osteosarcoma. Treatment included amputation of the penis and adjuvantdoxorubicin with carboplatin. Histopathology of the penis confirmed a haemangiosarcoma. The patient survived for 20 months. This is only the second published case report describinga penile haemangiosarcoma, and the first published report demonstrating the treatment and outcome of a case of haemangiosarcoma of the os penis. Based on published and unpublished reports, haemangiosarcoma appears to be the most common neoplasm of the canine penis.