Key Points

Prostate cancer in dogs is highly aggressive with local invasion and spread to regional lymph nodes common

Currently, no good treatment is available for this type of cancer

Prognosis is generally poor

Introduction

• The prostate is a accessory sexual organ that produces fluid that is a substantial component of the ejaculate
• Prostate cancer is uncommon in dogs with an estimated prevalence of 0.2 to 0.6%.
• Various types of prostate cancer exist with prostate carcinoma being the most common.
• This type of cancer is highly invasive and commonly spreads to lymph nodes. Less commonly, this cancer spreads to the lungs and lumbar vertebrae (spine).
• Unlike in man, castration has no effect on the progression of the disease, and castration even at a young age has not been shown to definitively decrease the risk for the development of this type of cancer.
• Canine prostatic carcinoma resembles a late stage, hormonally independant prostatic carcinoma in men.

Signs

• Blood in the urine
• Painful urination
• Straining to urinate
• Dribbling urine
• Weight loss
• Vomiting
• Constipation
• Hindlimb weakness
• Hindlimb lameness

Diagnosis

• Blood work is used to help evaluate the patient’s internal organ health
• Abdominal ultrasound will show the presence of a mass located in the prostate
• Biopsy of the prostate is needed to confirm the diagnosis

Treatment

• Castration usually has no benefit in dogs that have prostatic cancer
• Removal of the prostate is not recommend in dogs because urinary incontinence is invariably a complication of the procedure
• Interestingly, removal of the prostate in normal dogs infrequently causes incontinence. This suggests that the cancer may be involved in development of the cancer rather than the surgery in itself.
• If removal of the prostate is attempted, careful preservation of the nerves that lie along side of the prostate is essential. One study used a laser to remove most of the prostate in dogs that had prostate cancer and 3 of 8 dogs had major complications that necessitated euthanasia within 16 days after surgery. Median survival time was 103 days, with a maximum survival time of 239 days. All dogs ultimately had recurrence of clinical signs due to tumor regrowth.
• Another study evaluated the use of transurethral electrocautery to remove portions of prostatic cancer, however due to the poor results, this technique is not recommended.
• For the most part only chemotherapy is recommended to try to shrink the prostate. Unfortunately, this treatment usually fails to give the patient clinical relief of clinical signs and usually does not increase survival.

Prognosis

• The prognosis for prostatic cancer is poor

References

1. L’Eplattenier HR, Van Nimwegen SA, Van Sluijs FJ, et al. Partial Prostatectomy using NdYAG Laser for the management of canine prostatic cancer. Vet Surg 2006;35:406-411.
2. Liptak JM, Brutscher SP, Monnet E, et al. Transurethral resection in the management of urethral and prostatic peoplasia in 6 dogs. Vet Surg 2004; 33:505-516.