Should you consider prostatic disease?

Signalment

Canine, Dachshund, 6-year-old, male, 22 lbs.

Clinical history

The case history includes that the dog presents Dec. 7, 2001 for chronic diarrhea and recurrent urinary tract infection. The owner often feeds table food, and the dog will eat whatever he finds. Last May, the dog presented with bloody urine (and hemoglobinuria) and was treated with cephalexin and prednisone. The dog improved for a few days then had diarrhea. In October, a urinary tract infection was diagnosed and treated with enrofloxacin and prednisone. And in September, another urinary tract infection was diagnosed and treated.

Photo 1

Physical examination

The findings include rectal temperature 101.8 degrees F, heart rate 120/min, respiratory rate 30/min, pink mucous membranes, normal capillary refill time and normal heart and lung sounds.

On abdominal palpation, there is pain noted in the caudal abdomen and an enlarged prostate gland palpated easily through the abdominal wall. The dog is obese.

Laboratory results

A complete blood count, serum chemistry profile and urinalysis were performed and are outlined in Table 1.

Radiographic review

Survey thoracic and abdominal radiographs were done. The thoracic radiographs are normal. The abdominal radiographs show an enlarged liver and prostate gland. A double contrast cystogram was performed and showed an enlarged prostate gland and a normal urinary bladder displaced cranially.

Interestingly, two small stones were removed via the urinary catheter during the contrast radiographic procedure.

Photo 2

Ultrasound examination

One week after the survey and contrast radiography was performed, thorough abdominal ultrasonography was performed by a mobile ultrasound service.

The dog was positioned in dorsal recumbency for the ultrasonography.

My comments

The liver shows uniform echogenicity. There is increased echogenicity of the secondary portal vessels in the left lateral lobe. No obvious masses noted within the liver parenchyma. The gallbladder is mildly distended and its walls are not thickened or hyperechoic.

The spleen has uniform echogenicity - no masses noted. The left and right kidneys are similar in size, shape and echotexture. No masses or calculi were noted in either kidney. The urinary bladder is distended with urine and contains a moderate amount of urine sediment material - no masses or calculi noted.

There does appear to be blood clots attached to the wall of the urinary bladder. The prostate gland is enlarged and inhomogeneous in echotexture. The left prostate lobe appears to be more hypoechoic compared to the right prostate lobe. Hypoechoic lesions are visualized within the prostatic parenchyma. The stomach, small intestines and colon are normal. The pancreas shows uniform echogenicity. The adrenal glands are normal.

Case management

In this case, chronic prostatic disease and co-existing urinary tract infection are the clinical diagnosis. At this point, I would recommend doing a prostatic lavage for cytology and bacterial culture, ultrasound-guided fine needle aspirations of the prostate gland for cytologic examination and/or ultrasound-guided prostatic biopsies for histopathologic examination. Because ultrasonography was not readily available, a prostatic lavage was chosen.

Table 1

Prostatic fluid analysis

In a protein background, there are numerous large mononuclear cells and scattered epithelial cells with mild to moderate anisokaryosis.

Presumptive Diagnosis: Prostatic hyperplasia with mild inflammation.

Prostatic Fluid Culture Results: An Enterococcus species was cultured from the prostatic fluid. The bacterial isolate is resistant to clindamycin, cephalothin, gentamicin, amikacin, methicillin, penicillin, trimethoprim-sulfa, tetracyclines, ciprofloxacin and enrofloxacin.

My management of chronic prostatitis in this dog is immediate castration and long-term antimicrobial therapy. One will need to follow the dog's urination pattern since multiple blood clots were noted within the lumen of the urinary bladder.

Canine prostatic disease

The prostate gland in middle-aged to older dogs often experience diseases such as benign hyperplasia, prostatitis, prostatic cysts, prostatic abscesses and prostatic neoplasia. Treatment of choice for most prostatic diseases is castration. What is the medical treatment when castration is not an acceptable treatment choice?

Canine prostatic disease may be managed with the administration of 5-alpha-reductase inhibitors. If a dog is used for breeding and castration is not a desirable option, medical treatment is indicated for all prostatic diseases except neoplasia.

Dogs medicated with 5-alpha-reductase inhibitors will experience a significant decrease in prostatic size. Inhibiting 5-alpha-reductase blocks the conversion of testosterone to dihydrotestosterone within the prostate gland, protecting the prostate gland from the effects of androgens.

The 5-alpha-reductase inhibitors do not affect semen quality, so the dog can still be used for breeding. The two preferred drugs that block testosterone are megestrol acetate and finasteride.

Megestrol acetate has been used effectively to inhibit 5-alpha-reductase at an oral 0.55 mg/kg given once a day for six to eight weeks. Finasteride (Proscar, Merck) is a 5-alpha-reductase inhibitor approved for use in men. The dose in dogs is the same as in people: 5 mg given orally once a day for six to eight weeks.

Treatment may be repeated as needed over time. Because all treatment benefits with either drug appear within the first six weeks of therapy, it is not advisable to treat for longer periods. Some treated dogs experience a decline in libido.

Recurrent urinary tract infections in dogs are especially common. The way I generally manage recurrent urinary tract infections in dogs of all ages is:

First, I diagnose and manage any underlying cause for the problem such as the chronic prostatic disease in this case. Then, I administer appropriate antimicrobial therapy to the affected dog until the urine cultures negative - this usually requires standard antimicrobial therapy for at least four to six weeks. Thereafter, the dog receives a single standard dose of the respondent antimicrobial each evening after complete emptying of the urinary bladder for the night, usually around 10-11 p.m. By administering the antimicrobial agent to the dog each evening, it should concentrate in the collecting urine during the night for an immediate antimicrobial effect and should help maintain a delayed antimicrobial effect that is known to occur with many antimicrobial agents in the urinary tract.

This means that the antimicrobial agent will be incorporated into the surface epithelial cells of the urinary tract and maintain a bacteriostatic effect for an extended time period, which will vary with the antimicrobial agent used.

How long one should use the daily evening dosing of an antimicrobial agent for recurrent urinary tract infection is unknown. It may be for months to years depending somewhat on the medical history and active clinical problems of the affected dog.

I suspect some recurrent urinary tract infections are related to impaired immune regulation in the urinary tract, and these types of cases may require antimicrobial therapy for life.