Benign Prostatic Hypertrophy (BPH) in Dogs
Dr. Douglas Brum
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.
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.
Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not improve rapidly.
Administer all medications as directed. Alert your veterinarian if you are experiencing problems treating your pet.
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.