Prostate disease

• Benign hypertrophy Prostate: benign hyperplasia and hypertrophy is most common prostatic disease.
• Other diseases:
  • Acute and chronic bacterial prostatitis Acute prostatitis.
  • Prostatic or periprostatic cyst Prostate: cyst.
  • Prostatic neoplasia Prostate: neoplasia.
  • Prostatic squamous metaplasia.
  • Prostatic calculi.
• Signs: depends on etiology - can include: urethral discharge, pyrexia, abdominal pain, hematuria, weight loss, dysuria.
• Treatment: castration, anti-androgens, antibiotics, surgery.
• Prognosis: good to poor.

• Asymptomatic.
• Tenesmus (especially on defecation).
• Urethral discharge (hemorrhagic or purulent) unassociated with urination.

• Caudal abdominal pain, reluctance to move (acute bacterial prostatitis).

• Hematuria.
• Weight loss.
• Dysuria/urine retention.
• Change in semen quality, hemospermia.

• Acute peritonitis, bacteremia, septic shock (acute bacterial prostatitis).

• >3 years (incidence increases with age).

• >10 years (neoplasia).

• No breed predilection.

• Prostatic massage: contraindicated bacterial prostatitis because may → bacteremia.

• Older dogs → altered androgen/estrogen ratio → benign prostatic hyperplasia, prostatic cysts (ductal occlusion or prostatic oversecretion) or bacterial prostatitis.
• Paraprostatic cyst occasionally originates from a uterus masculinus, in which case there is no direct connection between cyst and prostate.
• Urinary tract infection → prostatic infection.
• Prostatic squamous metaplasia develops due to an increased [estrogen] level, eg due to Sertoli cell tumor or iatrogenic.

• Intact male.
• age.

Specific

• Uncastrated male animal (benign prostatic hyperplasia).
• Urinary tract infection (prostatic infection).

• Disease → enlarged prostate → pressure on ventral rectum → partial fecal obstruction and tenesmus.
• If disease → involves prostatic urethra → difficulty or inability to urinate, most likely associated with neoplasia.
• Bacterial infections may → bacteremia → septic shock.
• Malignant neoplasms (5% of prostatic disease) → metastasize to sublumbar lymph nodes or lung.

• Fecal tenesmus.
• Reluctance to breed.
• Urethral discharge.
• Pyrexia.

• Fecal tenesmus.
• Urethral discharge unassociated with urination.

• Hematuria.
• Hemospermia.

• Weight loss.
• Abdominal pain/reluctance to move.
• Dysuria/urinary retention.

• If prostate is enlarged, it lies cranial to the pelvic inlet.
• Bilateral, symmetrically enlarged, non-painful prostate in benign prostatic hyperplasia. The median raphe is still palpable.
• Bilateral, symmetrically enlarged, painful prostate in acute bacterial prostatitis. Loss of the median raphe.
• Asymmetrically enlarged, smooth even surface on palpation in prostatic or periprostatic cyst.
• In chronic bacterial prostatitis the prostate is sometimes enlarged, asymmetrical, hard and non-painful on palpation.
• Asymmetrically enlarged, irregular, often painful in prostatic neoplastic disease.

• Caudal abdominal mass on palpation.
• Pyrexia.
• Weight loss.
• Urethral discharge.

• Lateral abdominal radiographs Radiography: abdomen prostatic enlargement pushing the colon/rectum dorsally.
  
  Contrast medium in bladder will help to distinguish bladder from prostate.
• Acute periosteal new bone formation on the cranial brim of the os pubis and ilia or on the lumbar vertebrae .
• Localized peritonitis.
• Thoracic radiographs Radiography: thorax indicated to rule out pulmonary metastases.

• Symmetrical enlargement, no change in echotexture in benign prostatic hyperplasia and mildly hyperechoic in bacterial prostatitis.
• Asymmetrical enlargement, mixed echogenicity in prostatic neoplasia or some chronic cases of bacterial prostatis.
• Asymmetrical enlargement, hyperechoic with hyperechoic sediment in prostatic abscess.
• Thin walled hypoechoic areas within or connected to the prostate in prostatic or periprostatic cysts.
• Combined disease possible.

• Bacturia; at least one positive urine culture on several samples.
• Hematuria Urinalysis: blood.
• Pyuria.
• Proteinuria Urinalysis: protein.

• Prostatic wash.
  
  
  Contraindicated if dog pyrexic and leukocytic.
• See prostatic wash Cytology: prostatic wash for technique.
• Culture may be positive (bacterial prostatitis), similar infections to urinary tract infection.
• Neutrophil degeneration (prostatic abscess).
• Semen analysis with fractionation prostatic fluid.
• Cystic fluid (prostatic cyst).
• Ultrasound-guided fine needle aspirate or biopsy.
• Neoplastic cells (prostatic neoplasia).

• Leukocytosis, left shift in severe prostatic infections or leukopenia in some cases.

• Increased liver enzymes (endotoxemia).

• Biopsy or fine needle aspiration.
• Benign prostatic hypertrophy.
• Prostatitis/abscess.
• Prostatic neoplasia.

• Abnormalities of prostate depend on underlying disease process.

• Metastases (sublumbar lymph nodes, lung).

• Localized peritonitis.
• Perineal hernia.

• Causes of caudal abdominal mass involving bladder, urethra, colon, rectum, sublumbar lymph nodes.
• Causes of fecal tenesmus: colon/rectum/anus disease.
• Causes of preputial discharge.

• Causes of reluctance to move: orthopedic/neuromuscular disease

• See individual diagnosis for details of treatment.
• BPH- neuter, anti-androgen therapy (Finasteride).
• Prostatitis- appropriate systemic antibiotics +/- aspiration abscess.
• Neoplasia- surgical resection.
• Radiation.

• Risk of sepsis and bacteremia high in acute bacterial prostatitis or prostatic abscess → close monitoring for first 48 h antibiotics.

Treatment

• In some chronic prostatitis cases, long-term antibiotics are needed to keep infection under control.

Monitoring

• Rectal examination to determine size of prostate.
• Subsequent prostatic (via prostatic washes or ejaculate) and urine or semen samples, taken one week and one month after finishing antibiotics, need to have a negative culture. Treat as a complicated UTI.
• Monitor development of metastases in neoplastic disease.

• Benign prostatic hypertrophy.
• Squamous metaplasia.
• Prostatic calculi.
• Prostatic cysts.

• Bacterial prostatitis.
• Prostatic abscess.

• Prostatic neoplasia.

• Reduction in size of prostate (2-3 weeks) in benign prostatic hypertrophy, prostatitis and cysts.
• Negative prostatic fluid culture and urine culture one month after finishing antibiotics.

• Recurrence or development of obvious metastatic disease following surgery for prostatic neoplasia.
• Development of prostatic abscess after prostatitis has not been well controlled by antibiotic therapy.
• If several prostatic diseases present concurrently (for instance infection/neoplasia) and not recognized.
• Tenesmus may continue due to a perineal hernia.
• Prostatectomy may → urinary incontinence.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Bommer N (2006) Treatment of prostatic diseases. UK Vet 11 (4), 17-23 VetMedResource.
• Bommer N (2006) A review of the pathophysiology of prostatic diseases. UK Vet 11 (3), 20-26 VetMedResource.