The prostate is an accessory sex gland in males that completely surrounds
the urethra at the neck of the bladder. The prostate produces fluid that is
added to the ejaculate when a male dog
mates. This fluid provides nutrients and assists in the sperm’s movement. The
three conditions that cause prostatic enlargement are benign prostatic
hyperplasia, prostatitis, and
cancer of the prostate.
The diagnosis of prostate enlargement is made by digital rectal examination,
during which the size, position, and firmness of the prostate gland is
assessed. Ultrasonography provides additional information and may be helpful in
guiding a needle into the prostate to obtain a biopsy-a procedure indicated
when cancer is suspected.
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This is an increase in the size of the prostate gland. The disease is
hormone-dependent and is influenced by testosterone. Benign prostatic
hyperplasia begins in sexually intact males at about 5 years of age and
progresses as the dog grows older. Thus, older dogs are more likely to have
As the prostate enlarges, it gradually expands backward and may eventually
obstruct the rectum, causing constipation and straining while defecating. The feces
may appear flat or ribbonlike. Defecation is difficult. Fecal impactions are
Rarely, the prostate pushes forward and presses on the urethra, causing
straining during urination. Blood in the urine can be a sign of benign
Treatment: Treatment is not necessary unless the dog has symptoms. Neutering
eliminates the stimulus for prostatic enlargement and is the treatment of
choice for dogs who are not intended for breeding. A significant decrease in
the size of the prostate gland occurs shortly after neutering.
An alternative to neutering is to administer megestrol acetate (Megace), a
synthetic derivative of progesterone. Megace decreases the size of the prostate
without impairing fertility, but long-term use may cause a dog to develop
diabetes mellitus or adrenal problems. Note that estrogens, because of
their potentially serious side effects, are no longer recommended for treating
benign prostatic hyperplasia.
Prostatitis is a bacterial infection of the prostate gland, usually preceded
by a bout of cystitis. Signs of acute prostatitis are fever, depression, vomiting, diarrhea,
painful urination. The dog may have an arched back or a tucked-up abdomen.
Blood-tinged or purulent secretions may drip from the prepuce. The prostate
gland is enlarged, swollen, and tender.
The disease can become chronic, with periodic flare-ups. Chronic prostatitis
is a significant cause of male infertility.
Treatment: Your veterinarian may want to collect prostatic secretions for
culture and cytology. Once the diagnosis is made, the dog is placed on an oral
antibiotic selected on the basis of culture and sensitivity tests. Antibiotics
have difficulty penetrating the swollen prostate, so long-term administration
Following treatment, the prostatic fluid should be recultured to ensure that
the infection has been eliminated. Neutering helps to resolve symptoms and
decreases the likelihood of recurrent prostatitis.
Prostate surgery may be necessary for dogs with serious complications, such
as prostatic abscess.
This type of cancer is rare in dogs. It is not influenced by testosterone,
so it can occur in both neutered and intact male dogs.
Treatment: This involves surgery and/or radiation therapy. In most cases the disease is far
advanced by the time it is diagnosed. Because prostate cancer in dogs is not
testosterone-dependent, neutering does not slow the progress of the disease.
Similarly, neutering does not protect against the development of prostate
WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"