Issue Description A gland located near the neck of the urinary
bladder of male dogs. The urethra passes through it shortly after
leaving the bladder. The purpose of the prostate is to produce some of
the fluids found in normal canine semen. Other Names Prostate Disease, Benign Prostatic
Hyperplasia, Squamous Metaplasia, Cystic Hyperplasia, Paraprostatic Cysts, Prostate
Bacterial Infection, Prostatic Abscess
Causes There are at least seven diseases affecting the
1. Benign Prostatic Hyperplasia - This is a non-cancerous
enlargement of the gland. It is associated with the hormone
testosterone and is the most common disease of the prostate.
2. Squamous Metaplasia - This is a non-cancerous enlargement of
the gland caused by excess amounts of estrogen. An estrogen-producing
tumor called a Sertoli cell tumor is usually responsible.
3. Cystic hyperplasia - This condition is usually secondary to
benign prostatic hyperplasia or squamous metaplasia. It is caused by
obstruction of the ducts that carry prostatic secretions to the
urethra. Multiple, fluid-filled cavities result.
4. Paraprostatic Cysts - These are fluid-filled cysts that
develop adjacent to the prostate when abnormal tissue remains from
embryonic development before the puppy was born. The cysts begin to
develop shortly after birth but may not cause problems or be detected
until the dog is several years old. 5. Bacterial Infection - Bacteria may enter and infect the
prostate by going up the urethra or by coming down the urethra from an
infection in the urinary bladder. It is usually associated with a
preexisting abnormality of the prostate, such as benign prostatic
6. Prostatic Abscess - This is a progressive form of a
bacterial infection. If the ducts that drain the prostate become
obstructed, bacteria are trapped in the prostate and form a walled-off
site of infection known as an abscess.
7. Prostatic Cancer - This form is much less common than all of
the others. It may be associated with hormones from the testicles,
adrenal glands, or pituitary glands or it may occur without any
association with hormones.
Dogs that are neutered before puberty have very little prostatic
tissue. Without the male hormone testosterone that is produced within
the testicles, the prostate gland does not develop. If we were to
surgically explore this area in one of these dogs, only a tiny bulge
would be noted in the urethra. The small size causes no harm to the
dog, since the only known function of the prostate is support and
nourishment of the sperm cells. If a mature dog is neutered, the gland
will shrink to less that one-fourth of its previous size. Within a few
months, its functional cells will cease all or nearly all production
of the supportive fluids.
Symptoms Enlargement of the gland is common with most
prostatic diseases. Since the urethra passes through it, enlargement
of the prostate compresses the urethra, and urination becomes
difficult. Complete urethral obstruction only rarely occurs, but an
affected dog will spend quite a bit of time urinating and produces a
stream of urine with a small diameter. The colon, located just above
the prostate, is sometimes compressed by an enlarged prostate. This
makes defecation difficult. In summary, a dog with prostatic
enlargement often has a history of straining to urinate and/or
In addition, some dogs with prostatic disease
will have blood in the urine. Bacterial infection of the prostate is
sometimes, but not always, involved with production of the bloody
Common symptoms of prostate disease, however, some
animals do not show symptoms:
Straining to urinate
Voiding small amounts of urine frequently
Blood tinged urine
Dripping blood from the penis
Constipation and straining to defecate
Holding tail slightly away from back end
Passing small thin tape shaped feces
Diagnosis The first step in diagnosis is to determine if
the prostate is enlarged. This is done by feeling its size either
through the abdominal wall or through the rectal wall. It may be
confirmed by radiographs (x-rays) or an ultrasound examination.
Because there are so many diseases of the prostate, it is necessary to
perform several tests to tell them apart. These tests include cultures
of the dog's urine, a microscopic examination of the cells in the
urine, and a microscopic examination of the cells in prostatic fluid
or in the prostate itself. Samples of prostatic fluid are recovered by
passing a urethral catheter to the level of the prostate and massaging
the prostate to "milk" fluid out of it. Samples of prostatic cells are
obtained by aspiration or biopsy via a needle that is either passed
through the body wall or passed through the rectal wall. If the
prostate is greatly enlarged, it can be aspirated or biopsied through
the body wall; otherwise, an approach through the rectal wall is
necessary. An aspiration sample is taken through a very small bore
needle and only recovers a few cells. Sometimes this is adequate for
analysis; other times it is not. A needle biopsy sample is obtained
through a large bore needle that is passed into the prostate by
ultrasound guidance. A biopsy sample recovers a piece of tissue that
permits a pathologist to make a more accurate diagnosis.
Treatment 1. Diseases involving primary or secondary
bacterial infections are treated with aggressive antibiotic therapy.
Because it is difficult for antibiotics to penetrate into the
prostate, treatment for several weeks to months is usually necessary.
Since most of the infections are secondary to another disease,
treating the infection is only part of the overall treatment.
2. Diseases associated with excessive hormone levels include benign
prostatic hyperplasia, cystic metaplasia, and cystic hyperplasia.
Since testosterone and estrogen are both formed in the testicles,
neutering is generally an effective treatment for these conditions.
The prostate will generally return to normal within one month after
3. Paraprostatic cysts and prostatic abscesses require major abdominal
surgery to drain and remove.
4. Prostatic cancer does not respond well to any currently used form
of treatment. If it is associated with an excess of a hormone,
neutering may be beneficial; however, most are not and spread to other
parts of the body. The prognosis for these is usually poor.