No one knows what causes prostate cancer in dogs. While having a dog neutered can reduce the chance that a dog will develop prostate infections and/or prostate enlargement, it does not take away the risk of a dog developing prostate cancer. Even dogs that were castrated at a young age can develop canine prostate cancer. Unfortunately, the most common type of prostate cancer, carcinoma, is very invasive and it spreads aggressively. By the time the signs of prostate cancer are discovered, the cancer will usually have already spread to the lymph nodes, lungs and bones.
A dog that has prostate cancer will have changes in urination. The dog may urinate frequently and may not make it outdoors to urinate if it is an indoor dog. The dog may also seem to be in pain, or straining, when urinating. Blood in the urine is another sign of prostate cancer.
A top sign of canine prostate cancer is blood or pus discharging from the penis, or if the penis drips blood or pus.
A dog that has prostate cancer may have problems defecating. Constipation and straining is a sign of an enlarged prostate and prostate cancer.
Changes in the walking patterns of a dog are another sign of prostate cancer. Dogs with prostate cancer tend to take shorter steps. Their back legs may also appear stiff and rigid when they're walking.
Canines with prostate cancer will show changes in their behaviour and personality. They may be very lethargic and un-energetic. Things that would normally excite and interest dogs may no longer get more than a glance because the dog feels too ill to explore and play.