Prostatitis in Dogs

Dogs

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Prostatitis is a bacterial infection of the prostate gland. Infection of the prostate may be caused by disease of the urethra, which is the small tube where urine flows from the bladder through the penis, other urinary tract infections, or may be secondary to other forms of prostatic disease.

It occurs more commonly in intact (not neutered) male dogs, and older dogs are at greater risk than younger dogs. It occurs in both acute (sudden) and chronic (long standing) forms of prostatitis, but animals with the acute form are generally more debilitated than with the chronic form. It is not a significant clinical disease in cats.

Clinical signs of prostatitis vary with the severity of the infection and whether the disease is acute or chronic.

What to Watch For

  • Fever
  • Cloudy or bloody discharge from the penis
  • Blood in the urine
  • Abdominal discomfort
  • Stiff gait
  • Weakness
  • Lethargy
  • Straining to urinate or defecate
  • Anorexia
  • Vomiting
  • Weight loss
  • Chronic intermittent urinary tract infections
  • Infertility in a breeding male

    Diagnosis

  • History and physical exam including digital rectal exam
  • Urinalysis
  • Culture and sensitivity of the urine
  • Cytologic (microscopic) evaluation of seminal or prostatic fluid
  • Prostatic massage and wash for cytology, and culture and sensitivity
  • Abdominal radiographs (x-rays)
  • Abdominal ultrasound with or without prostatic aspiration
  • Clotting profile
  • Complete blood count
  • Biochemical profile

    Treatment

  • Antibiotics are typically given for a minimum 4 weeks
  • Intravenous fluids may be required in acute prostatitis
  • Analgesic or pain medications
  • Neutering may be recommended

    Home Care and Prevention

    Recheck examinations 7 to 14 days later are strongly suggested, as follow-up prostatic palpation is recommended. Abnormal blood tests should also be re-evaluated; the urine or a sample of the prostatic fluid may need to be re-cultured at this time.

    Make sure the urine color is becoming more clear if it was abnormal when your pet was ill. Your pet should continue to improve on therapy at home, but relapses may occur, especially with chronic disease. If there is any deterioration in condition, or recurrence of clinical signs, notify your veterinarian.

    Cultures of urine and or prostatic fluid might be recommended after finishing the antibiotics.

    Neutering a dog before reaching sexual maturity may decrease the incidence of prostatitis.

  • The most common cause of prostatitis is believed to be ascending infection from the urethra. The prostate can also become infected from infections in the bladder, kidneys or blood. If other forms of prostatic disease are present, such as cysts, neoplasia or squamous metaplasia, the prostate may be predisposed to developing a secondary infection. E. coli is the most common bacterium that causes infection.

    There are actually two different clinical presentations of prostatitis in the dog: acute and chronic. These two forms of the disease often present very differently, and require a different work-up and different therapy. In acute prostatitis, animals are usually quite ill and may even require emergency care. Animals are usually febrile and may have significant abdominal pain. Some dogs may even present with a critical blood infection (septicemia). On the other hand, dogs with chronic disease are generally much more stable or and have no clinical symptoms.

    Signs of chronic prostatitis are may be subtle and include: chronic intermittent urinary tract disease, intermittent discharge from the urethra, weight loss, and infertility in the breeding animal. Chronic prostatitis may develop after acute prostatitis is treated. Many times the diagnosis of the chronic disease is difficult to confirm and a prostatic biopsy is required for definitive diagnosis.

    Other diseases that may cause similar clinical signs as prostatitis include:

  • Urinary tract infections. Bacterial infections of the urinary bladder or kidneys may cause blood in the urine, fever and abdominal pain. It is not uncommon for an animal to have a urinary tract infection together with prostatitis.

  • 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. Animals may straining when they defecate or urinate, and most animals feel ill.

  • Benign prostatic hyperplasia (BPH). BPH is the most common form of prostatomegaly (increased prostate size), with virtually all intact male dog acquiring the condition as they age. It is caused by an increase in number and size of the prostate cells as the intact dog ages and is exposed to normal hormonal influences. It is a benign condition that usually does not cause any clinical signs. Occasionally a urethra discharge is present, which can be bloody. The majority of the time this condition is found incidentally on routine physical examination. Dogs with chronic prostatitis sometimes have very similar signs.

  • Prostatic neoplasia (cancer). Prostatic neoplasia may closely mimic chronic prostatitis. Animals with prostatic neoplasia 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 is high on the list of potential causes. Many times, a prostatic biopsy is required to differentiate chronic prostatitis from prostatic neoplasia.

  • Squamous metaplasia. Squamous metaplasia is a change in the prostate gland due to elevated blood estrogen levels. The main cause of this is an estrogen-producing tumor (Sertoli cell tumor). Long-term oral estrogen supplementation can also cause these changes. Sertoli cell tumors can also cause a chronic debilitating disease due to the suppressive effects of estrogen on the bone marrow.

  • A complete history and physical examination is the first step in obtaining an accurate diagnosis. An intact male dog with a fever, pain in the area of the prostate, and blood or pus in the urine has a high index of suspicion having acute pancreatitis. Dogs with acute prostatitis are usually quite ill and their prostate is generally painful. The diagnosis is usually more apparent in the acute condition and may require fewer diagnostics than in the chronic disease.

    Achieving a diagnosis of chronic prostatitis is more difficult as there are less consistent clinical signs. In chronic prostatitis, it is even typical that there is no prostatic pain. The diagnostic evaluation and potential results vary significantly depending if the disease is acute or chronic.

  • The CBC is a useful test to run in cases of prostatitis as it evaluates the red and white blood cells. Elevations in the total white count are commonly seen in acute prostatic infections. The white blood cell count in chronic prostatitis is commonly normal, although a mild anemia may be present.

  • The biochemical profile evaluates the metabolic status of a variety of organ systems. Since prostatitis is a more common occurrence on older animals, it is a useful screening test to rule out other problems and or associated disease. Liver and kidney function are evaluated. Blood sugar and electrolytes are also checked to provide a good overall assessment of the general condition of the patient. In dogs with acute prostatitis, or sepsis, hypoglycemia (a low blood sugar) and elevated liver enzymes may be present.

  • A urinalysis detects inflammatory changes or blood in the urine, and is generally the first test run when evaluating for prostatitis. The urine should be obtained sterilely for accurate interpretation. Animals with acute prostatitis usually show signs of infection (increased white blood cells and bacteria) in the urine. Conversely, dogs with chronic prostatitis may have a normal urinalysis, although intermittently they may present with urinary tract infections.

  • A culture and sensitivity of the urine helps to determine if a bacterial infection is present. A positive growth of bacteria is common with acute prostatitis. 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 chronic 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. Bacterial culture and sensitivities need 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 is a useful diagnostic tool when testing for prostatic disease. Samples are obtained via an ejaculate and the fluid is checked for evidence of white blood cells, red blood cells and bacteria. Since the prostatic fluid is concentrated in the last part (third fraction) of the ejaculate, this is the most productive part to analyze. The sample should also be cultured. This test is not often done, in a dog with acute disease since they are generally ill, depressed, and uncomfortable, making obtaining a sample difficult. In a dog with chronic prostatitis, this is an excellent test in obtaining evidence of infection. Many times when the urine shows no evidence of infection, the prostatic fluid collected will provide the information needed to support a diagnosis of chronic disease. Samples generally show signs of bacterial infection or hemorrhage.

  • A prostatic massage and wash is another method for evaluating prostatic fluid. 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. The fluid is then aspirated back through the catheter. This sample is submitted for cytology and culture. This technique is used most commonly chronic disease. Samples generally show signs of bacterial infection or hemorrhage.

  • Abdominal radiographs are useful in evaluating the abdominal organs and the extent of prostatic enlargement, but have limited use when diagnosing prostatitis. 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. The prostate may or may not be enlarged in cases of acute or chronic prostatitis. Occasionally, in the acute disease there is a lack of contrast, or detail, in the area of the prostate.

  • An abdominal ultrasound can evaluate the texture and consistency of the prostate, as well as size and shape. Cysts and abscesses are easily visualized. Changes in echogenicity (texture) 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.

    Cases of acute prostatitis usually do not require an aspirate or biopsy in order to obtain a tentative diagnosis. However, it may be very useful in chronic cases since ultrasound alone cannot differentiate chronic prostatitis from neoplasia or hyperplasia. Fine needle aspiration is less invasive than a biopsy, and may be used to collect fluid from cysts or obtain small cell samples from the prostatic tissue for cytologic evaluation (microscopic evaluation of the cells obtained). A biopsy, however, provides a better sample as a core of tissue is obtained for histopathology (microscopic examination of tissue). Biopsy usually provides more accurate information about the pathology of the prostate, since a larger amount of tissue can be evaluated.

  • Occasionally a clotting profile is indicated if there is significant bloody discharge from the penis or blood in the urine. Clotting tests to be considered might include an activated clotting time (ACT), a prothrombin time (PT), activated partial thromboplastin time (APTT), platelet count, and possible a von Willebrand's (VWF) test. Clotting tests are generally normal in prostatitis.

  • The treatment for prostatitis varies depending on whether the disease is acute or chronic. Acute prostatitis is a much more critical condition than chronic prostatitis and requires more immediate and aggressive care. When evaluating a dog for chronic prostatitis, it is generally appropriate to wait until a definitive diagnosis has been established prior to beginning therapy. In this way, appropriate antibiotic therapy may be started based on culture and sensitivity results. This may not be an option in some of the acute cases since the animal may require emergency treatment before the diagnostic test results are back.

    The decision as to when to begin therapy depends on the clinical assessment of the patient. In general, a more rapid treatment is required for the acute disease, and a longer treatment course is needed for the chronic condition. Although animals are sicker with the acute disease, it is generally easier to achieve a complete cure than with the chronic disease. Dogs with chronic prostatitis are more likely to have a continued intermittent problem despite therapy. Chronic prostatitis is a difficult disease to cure. Specific treatment includes:

  • Antibiotics. Antibiotics are the hallmark of treating prostatitis. The choice of specific antibiotics depends on the results of the cultures taken, and the ability of the antibiotic to penetrate the prostatic tissue. Not all antibiotics have an equal ability to enter the prostate (cross the blood-prostatic fluid barrier). Antibiotics that are effective include: erythromycin, clindamycin, chloramphenicol, trimethoprim/sulfonamide and the quinolones.

    In the acute condition, this choice is not as critical since the blood-prostatic barrier is not intact, and different antibiotics will penetrate the prostate effectively. Acute prostatitis is often treated with intravenous antibiotics initially, depending on the clinical condition of the animal. These antibiotics are usually started prior to receiving the results of the cultures. The antibiotics may be changed to an oral form once the pet is stable and culture results are back. Acute prostatitis is usually treated for a minimum of 4 weeks. In chronic prostatitis it is very important to base the choice of antibiotics on the culture results while choosing an antibiotic with good penetration into the prostate.

    Chronic prostatitis is more often treated for at least six weeks. In some cases, chronic prostatitis may not be curable. These animals may require life long antibiotic therapy. Antibiotics that are continued for life usually can be used at a lower dose.

  • Intravenous fluids. Intravenous fluids are sometimes needed in animals with acute prostatitis that are either dehydrated, in shock, or septic (bacterial blood infection). Fluid therapy maintains tissue perfusion, blood pressure and circulatory status in the critical patient.

  • Acute prostatitis can be quite painful. Providing pain relief while a diagnosis is pending will allow the dog to be more comfortable and to be able to rest. Narcotics and nonsteroidal anti-inflammatory drugs are most commonly used. Usually, pain medications are only needed during the initial in-hospital treatment of the patient. Animals with chronic prostatitis usually do not require analgesic medication.

  • Neutering. Animals with chronic prostatitis may benefit from castration. Castration decreases the hormone levels that stimulate the prostate, thereby causing the amount of prostatic tissue to shrink. Some dogs with chronic recurrent disease seem to have improvement of signs with neutering. Additionally, a certain number of dogs with acute disease may also go on to develop the chronic condition. Neutering may help the development of the more chronic disease.

    Follow-up

    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.

  • Animals with both acute and chronic prostatitis are prone to having repeated episodes of infection. Recheck physical examinations, prostatic palpation and good communication are important parts of continued care.

  • After finishing antibiotics, it is very important to have cultures repeated to assure that the infection has cleared. Urine and or prostatic fluid may be cultured. In cases of chronic prostatitis, an additional culture should be considered one month later.

  • If relapses are noted either by clinical signs or by a positive culture, antibiotic therapy will need to be continued on a more long- term basis. Antibiotics may need to be continued for months or potentially as life-long therapy.

  • In all cases of prostatitis, antibiotics are used for a fairly long duration. Depending on the antibiotic your pet is on, you should be aware of any potential side effects of long term administration. All antibiotics can cause gastrointestinal signs like diarrhea, but some may have more individual effects. Potential side effects should be discussed with your veterinarian.

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