Written and reviewed by John A. Bukowski, DVM, MPH, PhD
and Susan E. Aiello, DVM, ELS
Prostate cancer usually develops in older, intact male dogs, but it can also be seen in dogs that have been neutered.
Signs of prostate cancer often relate to the unique location of the prostate, which surrounds the urethra as it passes between the rectum and the pelvis.
Prostate cancer can lead to difficulty urinating, as the swollen or enlarged gland constricts the urethra and blocks urine flow. It can also cause straining to defecate, because the swollen gland can push up on the colon, blocking the passage of feces. Infiltration of the cancer into the spine or pelvis can cause difficulty walking and pain in the rear legs. Other signs may include fever and bloody urine.
The first step in diagnosing prostate cancer involves a thorough physical examination, including rectal palpation.
Your veterinarian will insert a gloved finger into the rectum to check the size and shape of the prostate gland. Your vet will also want to perform x-rays or ultrasound to get a visual picture of the gland, and to see if there are signs that the tumor has moved into nearby tissues. There is no prostate-specific antigen (PSA) blood test in dogs, like there is in people, but your vet will likely perform blood tests and/or a urinalysis to rule out infection.
Treatment of canine prostate cancer is difficult, because removal of the diseased gland tends to lead to permanent urinary incontinence.
In addition, most prostate tumors are malignant and have infiltrated nearby organs by the time signs become evident, so that even if the gland is removed, the cancer is not completely eliminated. Chemotherapy is not very useful. Some cases respond to radiation therapy, but this may also result in urinary incontinence. Overall, the prognosis for long-term quality of life is poor.
However, it is important to distinguish prostate cancer from a noncancerous, enlarged prostate, which can be effectively treated by neutering.
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