Prostatic Abscess in Dogs

Overview of Canine Prostatic Abscess

A prostatic abscess is a localized walled off pocket of infection within or adjacent to the prostate gland. The contents of an abscess contain white blood cells, bacteria, and cellular debris. Abscesses may form within the prostate gland in cases of chronic (long term) prostatic bacterial infections.

Prostatic cysts may become infected and lead to large abscesses within or next to (but connected to) the prostate. They may get to be quite large and cause compression of both the colon and urethra.

Prostatic abscesses occur rarely in dogs and never in cats. They occur more commonly in intact (not neutered) male dogs, and older dogs are at greater risk than younger dogs. All breeds may be affected.

The clinical signs associated with a prostatic abscess vary from subtle to severe.

What to Watch For

Symptoms of Prostatic Abscess in Dogs may include:

• Lethargy
• Depression
• Anorexia
• Abdominal discomfort
• Straining to urinate or defecate
• Fever
• Discharge from the penis
• Vomiting
• Weakness
• Collapse

Diagnosis of Prostatic Abscess in Dogs

• History and physical exam including digital rectal exam
• Complete blood count
• Biochemical profile
• 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)
• Distention retrograde urethrocystography
• Abdominal ultrasound with or without aspiration
• Surgical exploratory

Treatment of Prostatic Abscess in Dogs

• Intravenous fluids and intensive care support
• Intravenous antibiotics are given initially, then followed by long term oral antibiotics
• Urinary catheterization
• Analgesic (pain medications) therapy
• Ultrasound-guided prostatic abscess aspiration
• Exploratory surgery for surgical drainage of the abscess
• Castration

Home Care and Prevention

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

Cultures of urine and or prostatic fluid might be recommended after finishing the antibiotics. Abdominal ultrasounds may need to be followed postoperatively to ensure the resolution of the abscess.

Your pet should continue to improve on therapy at home, but relapses may occur. If there is any deterioration in his condition, or recurrence of clinical signs, notify your veterinarian.

Neutering a dog before reaching sexual maturity may decrease the incidence of prostatic abscess formation.

In-depth Information on Prostatic Abscess in Dogs

The location and anatomy of the prostate is important in understanding the clinical signs associated with prostatic abscesses. The prostate is located just behind the urinary bladder and under the colon. The prostate encircles the urethra – the tube that carries urine from the bladder through the penis and out of the body – as it exits the bladder. The prostate is made up of two symmetrical parts, or lobes, located on either side of the urethra. When the prostate is small it sits within the pelvic canal, but as it increases in size, it moves forward into the abdomen.

The clinical signs of prostatic abscesses vary with the type and severity of the prostatic disease. Prostatic abscesses usually arise from chronic infections of the prostate gland. The abscess forms as the immune system attempts to isolate, or wall off, an area of infection. E. coli is the most common bacterium that causes prostatitis and abscessation. There may be single or multiple abscesses within the prostate. The abscess can be small or very large. The largest abscesses probably develop from paraprostatic cysts (large fluid filled sacs connected to the prostate by a thin stalk) that become infected. These abscesses may become large enough to put pressure on other internal organs.

When the abscess enlarges to the point of putting pressure on the colon and decreasing its functional diameter, your dog will strain when defecating (tenesmus). The occasional “ribbon-like” appearance to the stools is a result of this compression. The decreased diameter can also result in constipation. If the abscess places pressure on the urethra, your dog will also strain when he urinates and there will be a urethral obstruction. Dogs with prostatic abscesses are usually ill. They may have either acute (rapid) or chronic (long standing) illness.

Animals may become critically ill if there is a urinary obstruction, or if the bacterial infection has spread to the blood (septicemia). Occasionally a large thin walled abscess may rupture, and release it’s contents into the abdominal cavity. This requires emergency treatment, as peritonitis, or inflammation within the abdominal cavity, and possibly septic shock would result. Other diseases that may cause similar signs as a prostatic abscess include:

• Paraprostatic cysts. Paraprostatic cysts are fluid-filled sacs that are connected to the prostate by a thin stalk. The cysts may be developmental in origin and arise from remnants of fetal tissue that normally degenerates (uterus masculinus). The cyst can also be directly of prostatic origin. Cysts can occur singly or in multiples, and they can get very large. Animals usually only feel ill if the cysts become large enough to compress other internal organs.
• Prostatic neoplasia (cancer). 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.
• Acute prostatitis. Prostatitis is a bacterial infection of the prostate gland. Usually, the prostate is painful to palpation, and the dog acts ill. A large prostate and a bloody discharge from the penis or blood in the urine are also common signs. Animals with the acute disease may also present critically ill with septicemia.

In-depth Information on Diagnosis of Prostatic Abscess in Dogs

A complete history and physical examination is the first step in obtaining an accurate diagnosis. If large enough the abscess may be palpable (felt) through the abdomen. More commonly, prostatic abscesses may be detected as a softer area on an enlarged, irregular prostate by digital rectal examination. A dog with a prostatic abscess may be quite ill and require a rapid diagnostic assessment. Other times, a critical situation is not present and the diagnostics may proceed in a more orderly manner.

• The CBC is a useful test to run when a prostatic abscess is suspected, as it evaluates the red and white blood cells. Elevations in the total white count are commonly seen in cases of infection and prostatic abscessation.
• The biochemical profile evaluates the metabolic status of a variety of organ systems. Since prostatic abscesses are a more common occurrence in older animals, and infection can affect other organ systems, it is a useful screening test to rule out other problems and or associated disease. Liver values may be elevated with the infection. If the abscess has compressed the urethra, a partial or complete urinary obstruction may occur, and cause an elevation in kidney values.
• A urinalysis will detect inflammation or blood in the urine, and may show signs of a bacterial infection. The urine should be obtained sterilely for accurate interpretation, and the urine should be cultured for bacterial growth. Dogs with prostatic abscesses may have a normal urinalysis, and have no bacterial growth on culture. The bacteria may be sequestered deep within the prostate or abscess and not be present in the urine at the time of sampling.
• 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 a prostatic abscess since they are generally ill, depressed, and uncomfortable, making obtaining a sample difficult. If a sample is obtained, it usually shows evidence of inflammation and infection.
• 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. Samples may show microscopic evidence of an infection.
• Abdominal radiographs are useful in evaluating the abdominal organs and the general size and shape of the prostate. The lymph nodes that drain the prostate (sub-lumbar lymph nodes) are also evaluated for enlargement. The prostate is usually enlarged on radiographs. Occasionally there is a lack of contrast, or detail, in the area of the prostate.
• Occasionally the abdominal X-rays may provide ambiguous results as to the nature of the prostatomegaly, especially if a large prostatic abscess or paraprostatic cyst is present. Distention retrograde urethrocystography is a technique where dye and air are injected through the urethra and into the bladder. This technique allows the urethral lining to be visualized and better defines the bladder, prostate and any associated mass lesions that may be present. It may be a useful diagnostic test to use if a compressive or invasive urethral lesion is suspected. This is most commonly seen in cases of prostatic neoplasia, paraprostatic cysts, or prostatic abscessation.
• An abdominal ultrasound can evaluate the texture and consistency of the prostate, as well as size and shape. Performing an ultrasound is helpful, even though the appearance of the prostatic abscesses on ultrasound is not specific for the disease. Prostatic cystic hyperplasia, hematomas (blood clots), and hemacysts, which are prostatic cysts that have bled into the cyst cavity, all have a similar appearance. In order to obtain a more specific diagnosis, an area that is identified as abnormal may be aspirated using the ultrasound for guidance.

Fine needle aspiration – inserting a needle into a structure and removing a small amount of cells or fluid with negative pressure using a syringe – may be used to collect fluid from abscess for cytologic evaluation. Extreme care and good judgment are needed when attempting this procedure since infected material from the inside of the abscess may leak out of the aspirated site and into the abdomen. Peritonitis would ensue, requiring rapid therapy. If this procedure is attempted, your veterinarian must be prepared for emergency surgery to flush out the abdomen and to treat the abscess. Even though this procedure caries a degree or risk, it may be the only way to diagnose the abscess other than exploratory surgery. Ultrasound-guided biopsy should not be attempted.

• Based on the above diagnostics, a prostatic abscess may be suspected, but the only way to diagnose a prostatic abscess definitively is either by ultrasound-guided aspiration or a surgical exploratory. Surgery becomes both a diagnostic and therapeutic procedure since surgical intervention is needed for treatment.

In-depth Information on Treatment of Prostatic Abscess in Dogs

Antibiotics are very important in the treatment of the infection; however, their effect is limited since they do not penetrate well into the abscess cavity. Antibiotic treatment, alone, may improve the clinical signs in the short term, but rarely would they lead to a cure. For this reason, surgical drainage of the abscess is needed if a cure is to be obtained. Since the surgery is technically difficult and requires intensive care monitoring post-operatively, cases are often referred to specialty hospitals with 24 hour critical care. Dogs require aggressive therapy after surgery. Septicemia and shock are common complications immediately post-operatively. The mortality rate within the first few days may approach 25 percent. Specific treatment of a prostatic abscess includes:

• Intravenous fluids and intensive care support. Most dogs with prostatic abscesses are very ill and the risks of shock and septicemia are significant. Fluid therapy maintains tissue perfusion, blood pressure and circulatory status in the critical patient. Some animals might even require transfusions with blood or plasma products.
• Intravenous antibiotics. 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 can cross the blood- prostatic fluid barrier 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 effectively into the prostate. Antibiotics are initially given intravenously, and an oral form is continued long-term at home. Antibiotics may need to be changed based on the culture results.
• Urinary bladder catheterization. In cases where the abscess causes compression of the urethra and a urinary obstruction, a catheter should be placed from the urethral orifice at the tip of the penis through the urethra and into the bladder. The goal is to by-pass the urethral blockage and allow for the normal flow of urine.
• A prostatic abscess 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 in the initial in hospital treatment of the patient.
• Ultrasound-guided prostatic abscess aspiration. Removing all or most of the fluid within the abscess by fine needle aspiration may be attempted if surgical drainage is not an option. It is generally not recommended as the treatment of choice since recurrences are likely, and peritonitis is a significant complication.
• Exploratory surgery for surgical drainage of the abscess. There are two surgical procedures for the drainage of a prostatic abscess. The procedure that is used depends on the size and location of the abscess and the surgeon’s preference. The first procedure involves opening the abscess, removing the fluid and placing a rubber drain inside the cavity. The drain is placed so it exits the abdomen through the skin. The drain is left in place, usually for 3 weeks to allow for continued drainage and the flushing of fluid into the cavity. The second procedure, called marsupialization, involves opening the abscess and suturing it to the exterior of the body. A permanent communication of the abscess wall and body wall is thus created. If possible, smaller abscesses and abnormal tissue should be removed.
• Castration. Dogs should be neutered at the time of the exploratory. Castration decreases the hormone levels that stimulate the prostate, thereby causing the amount of prostatic tissue to shrink. Neutering may also help in decreasing the potential of recurrence.

Follow-up Care for Dogs with Prostatic Abscess

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.
• Warm water compresses should be placed on the drain sites several times a day. The skin around the area should be kept clean.
• Close post-operative follow-up is important. Surgical sites need to be evaluated for appropriate healing. The amount and type of drainage should be recorded. The drainage should become clearer and the amount should decrease with time.
• Urinalysis and culture of the urine should be repeated frequently. Recurrent infections are common.
• Abdominal ultrasounds are periodically repeated. The ultrasound is used to assess the size of the prostate and it’s texture. The general size of the prostate should decrease but recurrence of abscesses may be discovered.