Overview of Canine Prostatomegaly (Enlarged Prostate)
Prostatomegaly is an increase in size of the prostate gland. It is common in the intact male dog, with almost all having the symptom as they age. Neutered male dogs are much less likely to have an enlarged prostate.
The general causes of prostatomegaly include:
Prostatomegaly may cause a wide variety of clinical signs. Most animals with prostatomegaly have benign prostatic hyperplasia and are asymptomatic, not showing any clinical signs. However, as the prostate enlarges or clinical disease is present, signs associated with prostatomegaly begin to appear.
What to Watch For
Diagnosis of Prostatomegaly in Dogs
Treatment of Prostatomegaly in Dogs
Specific treatment requires a specific diagnosis. General supportive care while a diagnosis is pending might include:
Close follow-up and rechecks are recommended to follow prostatic size. Most animals with enlarged prostates do not require emergency veterinary care. If your pet is ill, has a fever, or is very weak, veterinary care should be sought immediately.
In-depth Information on Prostatomegaly in Dogs
Prostatomegaly is a common clinical sign in older intact male dogs. As intact dogs age, testosterone and estrogen levels change, and with time, lead to a prostate gland that gradually enlarges. The prostate cells become larger and more numerous and often will form multiple small cysts throughout the prostatic tissue. This change (BPH) is a normal physiologic response to hormonal changes in the body and usually does not cause any clinical signs.
With intact male dogs, prostatomegaly is, many times, an incidental finding. Occasionally, if the growth of the prostate is excessive, the symptoms of prostatomegaly will be noted. If a dog is neutered prior to reaching sexual maturity, the usual prostatic growth is inhibited.
Dogs that have been previously castrated that present with prostatomegaly are at greater risk of having prostatic pathology (disease) than intact dogs with enlarged prostates. Some degree of prostatomegaly might be considered normal in the intact male. A more aggressive diagnostic approach is recommended in the neutered male dog with prostatomegaly since this is not a usual finding.
The physical examination of the prostate is important in providing useful information regarding the depth of the work-up required in evaluating prostatomegaly. The prostate generally can be palpated (felt) rectally or externally just in front of the dog's pelvis. If the enlarged prostate is painful or asymmetrical, further diagnostics are warranted. Asymmetrical prostates are more commonly associated with prostatic neoplasia or infections. Any history of weight loss or poor general body condition may indicate a more chronic (long term) condition.
Ill animals with large and painful prostates may have prostatitis or a prostatic abscess and would require more rapid attention. Acute or sudden infections of the prostate can be serious and may even spread systemically, causing septicemia (a blood infection). Rapid diagnosis and treatment will improve the prognosis and minimize the potential of sepsis.
Dogs that are straining to urinate or defecate should also be treated rapidly, as these animals are usually quite uncomfortable, and delays could lead to other problems. Severe constipation or a urinary obstruction might result, requiring emergency intervention. Fortunately, prostatomegaly is usually not an emergency situation, being a more chronic condition. This enables veterinarians to evaluate the patient carefully and to choose an appropriate diagnostic plan.
Causes of Enlarged Prostates in Dogs
The location and anatomy of the prostate is important in understanding the clinical signs associated with prostatomegaly. The prostate is located just behind the urinary bladder and under the colon. The prostate encircles the urethra, which is the tube that carries urine from the bladder through the penis and out of the body, as it exits the bladder.
The prostate is made up of two symmetrical parts, or lobes, located on either side of the urethra. When the prostate is small it sits within the pelvic canal, but as it increases in size, it moves forward into the abdomen.
The clinical signs of prostatomegaly vary with the type and severity of the prostatic disease. A urethral discharge is commonly seen with prostatic disease. Since the prostate communicates with the urethra, any increase in prostatic secretions may lead to a noted discharge.
Infection from prostatitis or a prostatic abscess may lead to a cloudy or purulent or pussy discharge. Bloody discharges may be seen with infections, tumors, or even BPH as an increased blood supply to the prostate may lead to hemorrhage. Clear or yellow discharges may be seen with cystic disease.
Your dog may also strain when he defecates when the prostate enlarges to the point of putting pressure on the colon and decreasing its functional diameter. The occasional “ribbon-like” appearance to the stools is a result of this compression. The decreased diameter can also result in constipation.
Paraprostatic cysts and prostatic abscesses are most commonly associated with this sign. The prostate generally enlarges outward, but if there is inward enlargement, pressure on the urethra may cause difficulty in urinating. This is an unusual presentation that generally only occurs with very significant enlargement as seen with paraprostatic cysts or abscesses. If the cysts or abscess is very large, distention of the abdomen may even be noted. Finally, animals with infections or tumors may feel ill, have a loss of appetite or have a more chronic weight loss.
The most common causes of prostatomegaly include:
A complete history and physical examination is the first step of obtaining an accurate diagnosis. It is very important to note if the dog is neutered or intact, as this will affect the diagnostic plan. A rectal exam is always indicated. Depending on the prostate's size and dog's conformation, the prostate (or part of the prostate) is usually palpable rectally. The size, shape, and texture of the gland are noted.
Prostatomegaly is much more common in intact older dogs. Many times the enlarged prostate is picked up as an incidental finding on the physical exam. If the prostate is smooth, not painful, symmetrically enlarged and the dog is not showing any clinical signs, the diagnosis of BPH is presumed, and no further work-up is recommended. In dogs neutered at a young age, the symptom of prostatomegaly should be investigated more aggressively.
The following tests may be indicated in some dogs having prostatomegaly:
Fine needle aspiration is useful in collecting fluid from cysts or obtaining small cell samples from the prostatic tissue. A biopsy provides a core of tissue for histopathology (microscopic examination of tissue), and usually provides more accurate information about the pathology of the prostate, since a larger amount of tissue can be evaluated. The ultrasound appearance of a dog's prostate with BPH generally shows a smooth capsule (covering) with the gland symmetrically enlarged. Small cystic areas may be noted that are usually well defined and have smooth margins. Biopsy is the only way to diagnose BPH definitively, but most times is not performed if the clinical presentation and history are typical.
Treatment of the symptoms might be needed while doing a diagnostic work-up, especially if the problem is severe. The following nonspecific (symptomatic) treatments may be applicable to some, but not all pets with prostatic enlargement. These treatments may reduce severity of symptoms or provide relief for your pet. However, nonspecific therapy is not a substitute for treatment of the underlying disease responsible for your pet's condition.