Male dogs may suffer from an inflammatory condition of the prostate gland. The proximity of the gland to the microflora of the distal urethra plays a role in this. Under normal circumstances, bacteria are prevented from reaching the prostate by these mechanisms:
1. Urine flow during urination
2, Pressure in the urethra
3. Urethral mucosal characteristics
4, Secretion of prostatic fluid and its antibacterial properties
5. The prostate may produce IgA in response to bacterial infection.
Infection is most commonly due to bacteria and may be caused by the same organisms as those which cause urinary tract infection. Anaerobes may be involved in abscess formation. Fungal infections are rare. E. coli is the most common bacterial pathogen involved. Benign prostatic hyperplasia occurs more often than infection of the prostate. Infection is usually a problem in intact male dogs.
Infections may be acute or chronic, with chronic infections the more common. 14% of intact male adult dogs have prostatic cysts as seen in hyperplasia. Up to 42% of cysts are infected with the same organism as seen in urine.
Pathogenesis is suspected to be as follows: Secondary migration of bacteria takes place up the urethra. It may also spread via blood, semen, urine and rectal flora. The bladder, prostate and urethra are close together and are often infected simultaneously. Prostatic fluid may reflux into the bladder and urine can enter prostatic ducts during micturition. Conditions which may cause an increase of bacterial numbers in the prostatic urethra, predispose to infection. This may include urolithiasis, neoplasia, trauma, stricture or lower urinary tract infection.
Acute bacterial prostatitis and abscess formation may cause septicaemia and severe clinical disease. Causative bacteria are not always isolated. Chronic prostatitis may develop insidiously, or may result from acute infection. Bacteria are not always isolated, A chemical inflammatory response resulting from urine reflux into the prostatic gland may be the reason for negative cultures in the presence of inflammatory prostatitis. Chronic infection and cyst infection may cause abscess formation. Rupture of abscesses cause peritonitis.
Diagnostic tests required are urinalysis and C&S. In cats or neutered male dogs treatment should continue for 10 days. Intact male dogs should be treated for 21 days. If infection persists, investigate kidney, bladder, prostate or other underlying prediposing conditions, as well as antimicrobial resistance.
The only antimicrobials used for genital tract infections which have good penetration to the prostate is enrofloxacin, marbofloxacin and tetracycline. E,coli has shown resistance to tetracycline.
Other antibiotics which may be considered for prostatitis are trimethoprim, fluoroquinolone,erythromycin and clindamycin.
Reference:
Blondeau JM. Steps to Antimicrobial Therapy, North America Compendiums Inc,2009, 109-113
