Osteosarcoma of the penile bone (os penis) in a dog.

Osteosarcoma of the penile bone was diagnosed in a 5-year-old neutered male Rottweiler with recurrent dysuria. Imaging and cytological findings raised the suspicion for an osteosarcoma and ablation of the entire penis and scrotal urethrostomy was performed. The diagnosis was confirmed histologically. The dog recovered well and no postoperative signs of dysuria were observed. The dog survived without adjuvant chemotherapy for 12 months when multiple tumours in the thorax and abdomen led to it being euthanased. Penile osteosarcoma is a rare disease, but must be considered as a differential diagnosis in dogs presenting with dysuria. This is the second recorded case of a penile osteosarcoma in a dog, but the first with a detailed description of the diagnosis, treatment and outcome.