Ask a UW Veterinarian: Problems of the Prostate

The question below was featured in the Spring 2019 issue of On Call, the magazine for friends of the UW School of Veterinary Medicine. This expert response comes from clinical assistant professors and board-certified specialists Michelle Turek (Medical and Radiation Oncology) and Elizabeth Alvarez (Primary Care).

Question: Have you made any progress in prostate cancer for male dogs and, if so, what are your suggestions for early onset of prostate enlargement? Also, why does prostate enlargement occur? –Jo Elliott, Belvidere, Illinois

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Answer: In both dogs and people, prostate development is hormone (testosterone) dependent. As male dogs age, hormone stimulation causes prostate enlargement called benign prostatic hyperplasia (BPH). BPH isn’t always problematic, but if the prostate gets big enough, it can lead to difficulty with urination and defecation. Routine veterinary examinations, including rectal examinations, aid in diagnosing prostate enlargement prior to the development of clinical signs.

Neutering prevents prostate enlargement and causes regression of BPH. However, unlike in human men, testosterone stimulation in dogs is not related to the development of prostate cancer. Thus, neutering is not protective against canine prostate cancer.

Dogs with prostate cancer show symptoms like straining to urinate or defecate, urinary obstruction, bloody urine, or ribbon-like stools. Unfortunately, these tumors often
spread to other parts of the body. Metastases to lymph nodes and lungs are most common. Bone metastasis, resulting in bone pain and abnormal gait, can also develop. New, minimally invasive molecular tests allow for easy diagnosis of canine prostate cancer.

Although there is no cure, treatment can temporarily relieve symptoms and extend life. In early cancer, surgical removal of the prostate is considered. Most dogs are diagnosed with advanced disease, at which point surgery has a higher risk of complications, so it is rarely recommended. Delivery of targeted radiation therapy allows for improved treatment of the cancer without significant side effects. When relief from urinary obstruction is needed, placement of a stent in the prostatic urethra improves urine flow. Chemotherapy is often recommended to slow the cancer and address the risk of metastasis. Nonsteroidal anti-inflammatory drugs can dramatically improve the quality of life of dogs with prostate cancer.