Pathological fracture of the os penis secondary to primary urethral urothelial carcinoma in a dog

Abstract A 12‐year‐old, male, neutered poodle was presented with a 1‐week history of intermittent penile bleeding, occurring both during and independent of urination, without signs of stranguria or dysuria. Physical examination revealed crepitus at the os penis, and radiographs confirmed an incomplete fracture of the os penis. Initial conservative management failed to improve the condition, prompting further investigations. Abdominal ultrasonography revealed no abnormalities of the kidneys, bladder or prostate; however, a mass‐like lesion at the fracture site was identified. Ultrasound‐guided fine‐needle aspiration of the mass was consistent with urothelial carcinoma. Thoracic radiographs obtained before surgery showed no evidence of metastasis. The dog subsequently underwent penile amputation and scrotal urethrostomy. Haematuria resolved within 10 days postoperatively. This case report aims to raise awareness of pathological fractures of the os penis caused by primary urethral urothelial carcinoma, both of which are rare conditions.