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Benign Prostatic Hyperplasia

Benign Prostatic Hyperplasia: An Overview

Benign Prostatic Hyperplasia (BPH) is where the prostate increases in size. It is the most common disease of the prostate, and occurs in almost all intact (non-neutered) male dogs as they age. An increase in size, or hyperplasia, is a non-cancerous change that generally does not cause clinical problems. The prostate is located just behind the bladder and has two main parts or lobes. Above the prostate is the colon. Dogs with BPH usually have a symmetrical enlargement of both lobes. The enlargement is not painful. Some breeds, such as the Scottish Terrier, have larger prostates than other dogs.

Causes of Benign Prostatic Hyperplasia

BPH is caused by age-related hormonal changes in the ratio of androgens, such as testosterone, and estrogens. Most dogs show no signs of BPH, but if there is a very large amount of prostatic hyperplasia, a dog might become symptomatic.

Prevention of Benign Prostatic Hyperplasia

The only prevention for BPH is to have your dog neutered.

Symptoms of Benign Prostatic Hyperplasia

Some of the signs to look for include:

  • Straining to defecate: An enlarged prostate (prostatomegaly) gland may cause changes in bowel movements if it grows large enough to put pressure on the colon.
  • Straining to defecate or occasionally forming stools that appear flat, long or ribbon-like, is common.
  • Intermittent or persistent bloody urine: An increase in prostatic blood vessels, or vasculature, and the increase in blood supply may lead to occasional bloody urine or a bloody discharge from the penis.
  • Discharge from the penis: BHP can cause intermittent bloody or clear yellow discharge from the penis.

Even when a dog is showing symptoms, he usually feels fine. However, when an enlarged prostate is found on physical, it is important to rule out the causes.

Diagnosing Benign Prostatic Hyperplasia

Diagnosis is made by performing several exams:

  • History and physical exam, including digital rectal exam
  • Urinalysis
  • Culture and sensitivity
  • Cytologic (microscopic) evaluation of seminal or prostatic fluid
  • Abdominal radiographs (x-rays)
  • Clotting profile
  • 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)

Treating Benign Prostatic Hyperplasia

No treatment is needed if the dog is asymptomatic (has no clinical signs.) However, it is good to observe for symptoms associated with an enlarging prostate.

Neutering (castration): Neutering is by far the most effective treatment for BPH. Neutering removes the source of hormonal stimulation and the prostate rapidly becomes smaller. Within days of castration, the prostate begins to shrink, and is usually 50 percent smaller within three weeks. Once neutered, any clinical signs previously present should improve significantly.

Estrogen Therapy: If neutering is not an option, low dose estrogen therapy may be used. Estrogen interferes with the hormonal stimulation of the prostate gland, and thus decrease the prostate's size. There are potential side effects with estrogen use so your dog should be monitored. For example, estrogen can cause bone marrow suppression leading to a decrease in white blood cells, red blood cells or platelets. Prolonged and higher doses of estrogen can even lead to squamous metaplasia (non-cancerous enlargement due to an estrogen-producing tumor called a Sertoli cell tumor.) Discuss the advantages and disadvantages with your veterinarian.

Ketoconazole (Nizoral): Ketoconazole is an anti-fungal drug that blocks the secretion of stimulating hormones from the testis. It can cause a decrease in prostate size, but is expensive.

Other drugs that have had limited success in a research setting are flutamide, megestrol acetate, and finasteride, but these drugs are not approved for use in the dog.

Caring for Dogs with Benign Prostatic Hyperplasia

Dogs that are asymptomatic and not receiving any therapy should have yearly or twice yearly physical examinations and owners should monitor their dogs for any potential changes. Follow-up is critical for any therapies. If you neuter your dog, be sure to have him rechecked two to three weeks after the surgery to make sure that the prostate is involuting (shrinking in size). If using estrogen, be sure to ask your vet about a CBC and platelet count to make sure the dog?s bone marrow is not being suppressed or damaged. The blood work will need to be rechecked multiple times over the course of therapy. When using ketoconazole, periodic CBCs and biochemical profiles should be performed.

The AKC Canine Health Foundation and Benign Prostatic Hyperplasia

One grant to study benign prostatic hyperplasia has been funded by CHF. This grant studied a new treatment for BPH that would not affect fertility.

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