Prostatomegaly (Enlarged Prostate) in Dogs


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:

  • Benign prostatic hyperplasia (BPH) or cystic hyperplasia. This is the most common cause of prostatomegaly.
  • Squamous metaplasia. This is enlargement of the prostate gland caused by excessive exposure to estrogen.
  • Prostatitis. This is a bacterial infection of the prostate gland.
  • Prostatic abscess. This is a severe form of prostatitis where a pocket of infected fluid develops within the prostate.
  • Paraprostatic cysts. These are large fluid-filled sacs connected to the prostate by a thin stalk.
  • Prostatic neoplasia. Tumors of the prostate gland are all malignant and difficult to treat.

    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

  • Clear, cloudy, yellow or bloody discharge from the penis
  • Straining to pass stool
  • Passing stool shaped like a ribbon
  • Lethargy
  • Anorexia
  • Weight loss
  • Fever
  • Abdominal discomfort
  • Abdominal distention
  • Straining to urinate
  • Fertility problems in intact male breeding dogs
  • Chronic or recurrent urinary tract (bladder) infections
  • Diagnosis of Prostatomegaly in Dogs

  • History and physical exam, including digital rectal exam
  • Urinalysis
  • Culture and sensitivity of the urine
  • Cytologic (microscopic) evaluation of seminal or prostatic fluid, collected by ejaculate, with culture and sensitivity
  • Prostatic massage and wash for cytology, and culture and sensitivity
  • Abdominal radiographs (X-rays)
  • Abdominal ultrasound with or without prostatic aspiration – inserting a needle and syringe into the tissue and obtaining a small sample for cytologic analysis – or biopsy
  • Clotting profile
  • Complete blood count
  • Biochemical profile
  • Thoracic (chest) radiographs
  • Distention retrograde urethrocystography
  • Treatment of Prostatomegaly in Dogs

    Specific treatment requires a specific diagnosis. General supportive care while a diagnosis is pending might include:

  • Intravenous fluids
  • Intravenous antibiotics
  • Urinary catheterization
  • Analgesic (pain) medication
  • Enemas
  • Home Care

    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.


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