A castrated 9-year-old intact male boerboel cross-breed dog was presented with a month-long
history 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, which
was 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 penile
urethra. Radiographs demonstrated a soft tissue mass with osteolysis of the os penis. Cytology
suggested an osteosarcoma. Treatment included amputation of the penis and adjuvant
doxorubicin with carboplatin. Histopathology of the penis confirmed a haemangiosarcoma.
The patient survived for 20 months. This is only the second published case report describing
a 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 Based on published and unpublished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.