Introduction
Prostate cancer can affect male dogs of all breeds and ages, whether intact or neutered, although it normally is diagnosed in older dogs. Signs of prostate cancer often mimic the signs of other prostatic disorders, such as benign prostatic hypertrophy, prostate abscesses or prostatitis.
Symptoms of Prostate Cancer
The symptoms of prostate cancer usually develop gradually. Owners of affected dogs may notice none, one or more of the following symptoms:
- Frequent attempts to urinate
- Urination in abnormally small amounts
- Incontinence
- Straining to urinate (stranguria; caused by compression of the bladder by the mass)
- Difficulty urinating (dysuria)
- Blood in the urine (hematuria)
- Straining to defecate (tenesmus; caused by compression of the colon by the mass)
- Constipation
- Scooting
- Periodic watery, bloody discharge from the penis (serosanguinous discharge)
As the disease progresses, the dog may develop one or more of the following signs:
- Rear end lameness or other motor abnormalities (caused by metastasis of the cancer to bone)
- Increasing signs of pain
- Lethargy
- Loss of interest in playing, going for car rides or participating in other normal activities
- Loss of appetite (inappetance; anorexia)
- Weight loss (often dramatic)
- Fever (usually fluctuating)
- Holding the tail in an unusual position (due to localized discomfort)
Dogs with prostate cancer can exhibit one, some, all or none of these symptoms at varying stages of their disease. Ultimately, most prostate tumors will metastasize to distant locations, with or without treatment. If an older male dog exhibits any of these signs, his owner should consult with a veterinarian at the earliest opportunity.
Dogs at Increased Risk
Prostate cancer can occur in neutered or intact male dogs of any age. It typically occurs in older dogs, on average at about 10 years of age, depending upon breed. Large and giant breed dogs normally have a shorter life expectancy than do smaller dogs. As a result, they tend to develop prostate cancer earlier than other dogs. There is no recognized breed predisposition to development of prostate cancer. However, middle-sized, large and giant breeds seem to be more commonly affected.