Page 733 - Small Animal Internal Medicine, 6th Edition

CHAPTER 42 Bacterial Cystitis, Pyelonephritis, and Prostatitis in the Dog and Cat 705

TABLE 42.1
VetBooks.ir Definitions Applied to Urinary Tract Infections

TERM
DEFINITION
Sporadic bacterial Sporadic bacterial infection of
cystitis (i.e., the bladder in an otherwise
sporadic UTI) apparently healthy individual
with normal urinary tract
anatomy and function
Complicated UTI UTI that occurs in the presence of
an anatomic or functional
abnormality or comorbidity that
predisposes to persistent UTI,
recurrent infection, or treatment
failure FIG 42.1
Subclinical Presence of bacteria in the urine Photomicrograph of a section of the urinary bladder from a
bacteriuria as determined by a positive dog with C. urealyticum cystitis. Transitional epithelium
bacterial culture in the absence overlying the smooth muscle is completely denuded and
of lower urinary tract signs replaced by a thick mat of partially mineralized (basophilic)
degenerate cellular debris and fibrin exudates (arrow) (H&E;
(LUTS). Differentiation from bar = 100 µm). These plaques must be removed
subclinical UTI may be difficult. (cystoscopically or surgically) to allow antibiotics to
penetrate the bladder wall.
From Westropp J, Sykes JE: Bacterial infections of the genitourinary
tract. In Sykes JE, editor: Canine and feline infectious diseases, St.
Louis, 2013, Elsevier.

dysuria. In the author’s experience, some dogs with urinary
incontinence and positive bacterial urine culture respond
to antimicrobial therapy suggesting this is a clinical sign
associated with UTI. Subclinical bacteriuria has also been
referred to as occult UTI and asymptomatic bacteriuria in
human medicine.
Animals with comorbidities can have unique bacterial
infections such as Corynebacterium urealyticum, a gram-
positive bacterium that can result in encrusting cystitis (Fig.
42.1). This pathogen also can produce urease, which results FIG 42.2
in the precipitation of calcium phosphate and struvite Lateral radiograph of a 13-year-old female spayed Terrier
plaques that adhere to the uroepithelium. The most common mix with diabetes mellitus with emphysematous cystitis
cause is E. coli, which ferments the glucose to gas products; caused by E. coli. Note the irregular gas pattern within the
Clostridium spp. may also be involved. In the absence of bladder lumen.
glucose, proteins such as albumin may be fermented to gas.
Dogs and cats with diabetes mellitus may present with procedures are often required, and these tests are not clini-
emphysematous cystitis (EC), characterized by the produc- cally available. It is easy to identify a reinfection when the
tion of gas by bacteria within the bladder wall or lumen (Fig. quantitative urine culture reveals a different bacterial genus
42.2). Gas was most commonly detected in the bladder and species than the original isolate. The same organism
lumen and wall in 14/27 (51%) of dogs with EC in a recent isolated initially causes a relapsing infection; it can be caused
report. Comorbidities were identified in 26/27 (96%) cases by the persistence of an organism that was never completely
reported, the most common of which were diabetes mellitus eradicated. Relapse suggests the organism may be deep-
in 33% of dogs, neurologic disease in 26% of dogs, and seated in the tissues—inaccessible to the antimicrobial, as in
adrenal disease in 19% of dogs. the kidney, prostate, or polyps—or that subtherapeutic con-
Recurrent bacterial cystitis (UTI) implies that the animals centrations of the antimicrobial were achieved in the urine
have had three or more infections in a 12-month time period. and/or urinary tissues, or that the organism is resistant to
Recurrent UTI can be subclassified as relapsing infection, the chosen antimicrobial. A study reported that there was a
reinfection, refractory infection, or persistent infections. 17% disagreement between bladder mucosa cultures com-
Although urine bacterial cultures may help distinguish these pared with urine cultures suggesting deep-seated infections
types of recurrent infections, advanced molecular diagnostic may occur in dogs. This difference was not significant