Benign Prostatic Hypertrophy (BPH) in Dogs

Overview of Canine Benign Prostatic Hypertrophy (BPH)

Benign prostatic hypertrophy (BPH), or cystic hyperplasia, is an age related change of the prostate where the prostate increases in size. This increase in size, or hyperplasia, is a non-cancerous change that generally does not cause clinical problems. BPH is the most common disease of the prostate, and occurs in almost all intact male dogs as they age.

The increase in size is caused by hormonal changes in the ratio of androgens, like testosterone, and estrogens. Most dogs act normal, but if there is a very large amount of prostatic hyperplasia, a dog might become symptomatic.

What to Watch For

Signs of Benign Prostatic Hypertrophy (BPH) in Dogs may include:

• Straining to defecate
• Intermittent or persistent bloody urine
• Intermittent bloody or clear yellow discharge from the penis

Even if a dog is showing symptoms, he usually feels fine.

Diagnosis of Benign Prostatic Hypertrophy (BPH) in Dogs

• 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

Treatment of Benign Prostatic Hypertrophy (BPH) in Dogs

• No treatment is needed if the dog is asymptomatic
• Neutering
• Estrogen therapy
• Ketoconazole (Nizoral®)

Home Care and Prevention

If your pet is asymptomatic, that is he has no clinical signs, observe for symptoms associated with an enlarging prostate. If he’s neutered, any clinical signs previously present should improve significantly within a few weeks.

If the treatment involves neutering, the incision should be monitored for any swelling or discharge.

If medical management is attempted, careful monitoring of clinical signs and blood tests will be needed.

The only prevention for BPH is having your dog neutered.

In-depth Information on Benign Prostatic Hypertrophy (BPH) in Dogs

Dogs and men are the only two species that experience BPH, but it is so common that nearly every intact dog is affected as they age. 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 dogs, specifically the Scottish terrier, normally have larger prostates than other dogs. Most animals with BPH have no symptoms and feel fine. Many times the diagnosis is made on routine yearly physical examination.

When an enlarged prostate (prostatomegaly) is found on physical, it is important to rule out the causes of pathologic (disease causing) prostatic enlargement. The diagnosis of BPH, itself, is a benign condition that often requires no treatment. As dogs age, testosterone and estrogen levels change, and the prostate cells become larger and more numerous and often form multiple small cysts throughout the prostatic tissue. With time, this leads to a prostate gland that gradually enlarges.

Unlike in people, the enlarged prostate gland usually does not cause problems urinating, but occasionally may cause changes in bowel movements. A prostate may grow large enough to put pressure on the colon and compress its diameter. Straining to defecate (produce a bowel movement) may be noted. Occasionally, stools formed may be flat and long, like a ribbon, because as the prostate enlarges, the diameter of the colon becomes flattened.

Along with the increase in prostatic size comes an increase in prostatic blood vessels, or vasculature, and the increase in blood supply may lead to the occasional clinical sign of bloody urine or a bloody discharge from the penis. Other diseases that cause an enlarged prostate gland or similar clinical signs include:

• Prostatitis. Prostatitis is a bacterial infection of the prostate gland. Usually, the prostate is painful to palpation, and the dog often acts ill. A large prostate and a bloody discharge from the penis or blood in the urine are common signs. Prostatitis may be acute (sudden) or chronic (long term).
• Prostatic abscess. An abscess is a walled off pocket of infection containing white blood cells, bacteria, and cellular debris. Abscesses occasionally form within the prostate gland in cases of chronic prostatic infections. They may get to be quite large and cause compression of both the colon and urethra. Straining to defecate or urinate may be seen, and most animals are feeling ill.
• Paraprostatic cyst. Paraprostatic cysts are fluid-filled sacs that are connected to the prostate by a thin stalk. These can occur as a singular cyst or multiple cysts, and they can get very large.
• Prostatic neoplasia (cancer). Prostatic cancer may closely mimic other types of prostatomegaly, but usually dogs with prostatic cancer have an asymmetric enlargement of one of the lobes of the prostate. Animals with prostatic neoplasia also tend to be systemically ill and have a history of weight loss. Tumors of the prostate are almost always malignant. The most common tumors involving the prostate are adenocarcinoma and transitional cell carcinoma. In contrast to most other types of prostatic disease, prostatic cancer occurs with the same frequency in both intact and neutered dogs. In a neutered male dog with significant prostatomegaly, prostatic neoplasia would be high on the list of potential causes.
• Squamous metaplasia. Squamous metaplasia is a change in the prostate gland due to elevated blood estrogen levels. The prostate gland generally becomes bilaterally symmetrically enlarged. The main cause of this is an estrogen-producing tumor (Sertoli cell tumor). Long-term oral estrogen supplementation can also cause these changes.

Diagnosis In-depth

• A complete history and physical examination is the first step of obtaining an accurate diagnosis. Dogs with BPH are usually older and are intact males. They generally do not act sick, even if showing some clinical signs. Many times the enlarged prostate is picked up as an incidental finding on the physical exam.
• A rectal exam is always indicated. Depending on the prostate’s size and dog’s conformation, the prostate is usually palpable rectally. The size, shape, and texture of the gland are noted. Animals may be uncomfortable during the exam but are generally not painful. Many times a diagnosis of BPH is made on the basis of the physical findings and history alone.

The following tests may be indicated in some, but not all, dogs suspected of having BPH:

• A urinalysis to detect inflammatory changes or blood in the urine and to help in evaluating prostatic disease. The urine sample should be a sterile sample for accurate interpretation. Dogs with BPH usually will have normal urine or occasionally some blood.
• A culture and sensitivity of the urine to determine if a bacterial infection is present. A positive growth of bacteria indicates that a urinary tract infection is present. However, the results are not specific for a prostatic infection as an infection anywhere along the urinary tract (bladder, kidneys or prostate) may give positive results. Additionally, dogs with prostatic infections may not have any bacterial growth on culture as the bacteria may be sequestered deep within the prostate and not be present in the urine at the time of sampling. A bacterial culture and sensitivity needs to be interpreted with caution and should be evaluated in light of the total clinical presentation of the animal.
• Cytologic (microscopic) evaluation of seminal fluid. Samples are obtained via an ejaculate and the fluid is checked for evidence of infection, blood or tumor cells. The sample, ideally the third fraction of the ejaculate, can also be cultured if indicated. Dogs with BPH have normal seminal fluid with or without blood. This test is not often done, since obtaining a sample may be difficult.
• A prostatic massage and wash. There are several techniques for obtaining this sample. Briefly, a urinary catheter is passed to the level of the prostatic urethra and the prostate is digitally massaged through the rectum. A sample is obtained by flushing fluid into the area and then aspirating the fluid back through the catheter. The sample is then submitted for cytology and culture. Dogs with BPH have normal results.
• Abdominal radiographs to evaluate the abdominal organs and the extent of prostatic enlargement. The general size and shape of the prostate is noted, and the lymph nodes that drain the prostate (sub-lumbar lymph nodes) are evaluated for enlargement. With prostatic enlargement the colon may be pushed upward and compressed, while the bladder may be pushed further into the abdomen. If there is poor abdominal contrast in the area of the prostate, an abscess, neoplasia or cyst may be suspected. Abnormal calcification of the prostate is easily visualized radiographically and sometimes correlates with a neoplastic process. Infection can also cause these changes.
• An abdominal ultrasound to evaluate the texture and consistency of the prostate, as well as size and shape. Cysts and abscesses are easily visualized. Changes in texture (echogenicity) can be seen with any type of prostatic disease. Abdominal lymph nodes are observed for enlargement. In order to obtain a more specific diagnosis, an area that is identified as abnormal may be aspirated or biopsied using the ultrasound for guidance.

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.

• A clotting profile if there is significant bloody discharge from the penis or blood in the urine. Clotting tests might include an activated clotting time (ACT), a prothrombin time (PT), activated partial thromboplastin time (APTT), platelet count, and possible a von Willebrands (VWF) test.

Therapy In-depth

BPH is a benign condition that generally does not cause any clinical signs or problems, and thus does not require treatment. It is prudent to be advised of the situation and to be aware of any potential future clinical signs. The most important aspect of establishing a diagnosis of BPH is in ruling out other causes of pathologic (disease causing) prostatomegaly. When a diagnosis of BPH is made, or suspected, several treatment options are available:

• Observation. If a dog is asymptomatic no treatment is needed.
• Neutering (castration). By far the most effective method of treatment is neutering. With neutering, the source of hormonal stimulation is removed and the prostate rapidly becomes smaller. Within days of castration, the prostate begins to shrink, and is usually 50 percent smaller within three weeks.
• Estrogen therapy. If castration is not an option, low dose estrogen therapy may be considered. Estrogens interfere with the hormonal stimulation of the prostate gland, and thus decrease the prostate’s size. Estrogen does have potential significant side effects and careful monitoring is needed. 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 of the prostate and a corresponding increase in prostate size. The advantages and disadvantages should be carefully considered when choosing estrogen therapy.
• Ketoconazole (Nizoral®). This anti-fungal drug also blocks the secretion of stimulating hormones from the testis. It is an expensive drug that can cause a decrease in prostatic size.
• 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.

Follow-up Care for Dogs with Benign Prostatic Hypertrophy

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not improve rapidly.

• Administer all medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.
• In animals that are asymptomatic and not receiving any therapy, yearly or twice yearly physical examinations are a reasonable approach in monitoring for any potential changes.
• Once neutered, your dog should be rechecked two to three weeks after the surgery to make sure that the prostate is involuting (shrinking in size).
• If estrogen is being used, a CBC and platelet count is needed to make sure the 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 checked. Ketoconazole can cause gastrointestinal disturbances and elevations of liver enzymes. Watch for vomiting, diarrhea, and anorexia.