Abstract The canine prostate gland shares many morphological and functional similarities with the human prostate and dogs are the only other large mammals that commonly develop spontaneous prostate cancer. However, the incidence of prostate cancer is much lower in dogs and the precise cell of origin is not known. Dogs with prostate cancer usually present with advanced disease that does not respond to androgen deprivation therapy. Similar to humans, affected dogs often develop osteoblastic bone metastases in the pelvis and/or lumbar spine with associated pain and neurological deficits. Other clinical signs include weight loss, lethargy, and abnormal urination and/or defecation. Surgery, chemotherapy, and radiation have been used to treat dogs with prostate cancer, but success has been limited by the location and aggressive nature of the disease. It is evident that better methods of early detection and more effective therapies are needed for prostate cancer in dogs and advanced prostate carcinoma in men. Dogs with naturally-occurring prostate cancer are relevant models for the disease in humans and pre-clinical studies of new diagnostics and therapies in dogs may benefit both humans and dogs with prostate cancer.