Prostate Problems in Dogs
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.
Benign Prostatic Hyperplasia
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 symptoms.
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 common.
Rarely, the prostate pushes forward and presses on the urethra, causing straining during urination. Blood in the urine can be a sign of benign prostatic hyperplasia.
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, and 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 is necessary.
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 cancer.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
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