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234 Cystitis, Bacterial

• Abdominal ultrasound: identify radiolucent ○ Meropenem 8.5 mg/kg SQ (or IV) q • Many antibiotics are present in high con-
uroliths, thickened bladder wall or mass, ○ Fosfomycin tromethamine may be useful centration in the urine as a result of renal
8-12h
VetBooks.ir • Urinary contrast studies: identify radiolucent for E. coli UTI: 40 mg/kg PO q 12h for ○ Disk diffusion assays of sensitivity usually
evidence of pyelonephritis or prostatic disease
excretion:
evaluate expected serum drug concentra-
3 days
uroliths, bladder mass, evidence of pyelone-
• Other therapies may be used to reduce
phritis, urethral abnormalities
recurrence (see Prevention below). tion, and sensitivity of a uropathogen in
vivo may be greater than that predicted
TREATMENT in vitro.
Possible Complications ○ If expected urine concentration of
Treatment Overview • Emphysematous cystitis: rare complication antibiotic exceeds minimum inhibitory
Most uncomplicated UTIs respond readily resulting in gas formation in bladder wall; concentration by four times, the antibiotic
to a short course of antimicrobial drugs. most often identified in diabetic animals should be effective.
Complicated UTI may be very difficult to cure. • Pyelonephritis: vesicoureteral junction usually • Persistent bacterial cystitis usually results
prevents bacterial ascension to kidneys from inappropriate choice of antibiotic or
Acute General Treatment • Urolithiasis: struvite inadequate dose/duration of administra-
Antibiotic choices appropriate for empirical • Adverse reactions to antibiotics are possible tion, emergence of bacterial resistance to
treatment of uncomplicated infection or (e.g., TMS may cause keratoconjunctivitis the chosen antibiotic, or failure to correct
pending culture/sensitivity results in compli- sicca, gentamicin is nephrotoxic, enrofloxacin underlying illness or condition allowing
cated infection: is detrimental to cartilage in growing dogs infection to occur.
• Gram-positive infections: amoxicillin and, in high doses, may irreversibly damage • Subclinical bacteriuria is increasingly recog-
15-20 mg/kg PO q 8 -12h the feline retina). nized in animals. Antimicrobial therapy is
• Gram-negative infections: amoxicillin or generally not needed in such cases and may
trimethoprim-sulfadiazine (TMS) 15-30 mg/ Recommended Monitoring do more harm than good.
kg q 12h. Although often effective, fluo- • For uncomplicated infection, monitoring
roquinolones reserved for UTI resistant to clinical signs is adequate. Prevention
amoxicillin or TMS • For complicated infection, urinalysis may • Correction of predisposing illness or condi-
• Cefovecin 8 mg/kg SQ once has been used be repeated 7-10 days after completion of tions is the most effective strategy to prevent
off-label with good success (Enterococcus spp therapy. Even if bacteriuria persists, in the infection.
and Pseudomonas spp will be resistant). absence of clinical signs, additional antimi- • For animals in which predisposing factors
• Avoid antimicrobials with hepatic or crobials are likely unnecessary. If signs persist, cannot be corrected and recurrent infections
gastrointestinal rather than renal elimination repeat culture. are problematic, urinary antiseptics may be
(e.g., tetracyclines). • Periodic urine culture is no longer routinely warranted:
recommended for animals with risk factors ○ Antiseptics (dogs): methenamine mandel-
Chronic Treatment for UTI but without lower urinary signs. ate 10 mg/kg PO q 6-8h or methenamine
• Predisposing illnesses or conditions should hippurate 500 mg PO q 12h. Both effec-
be addressed. PROGNOSIS & OUTCOME tive in acidic urine; may require addition
• Duration of antibiotic therapy of ammonium chloride as acidifying agent
○ Uncomplicated: 5-7 days; shorter courses • Prognosis for uncomplicated infection is (60-100 mg/kg q 12h). CAUTION: urinary
may be adequate excellent. acidification may precipitate formation of
○ Complicated: optimum duration • Prognosis for complicated infection depends certain uroliths.
unknown; historically, 4 weeks or more on ability to correct predisposing illness or ○ Alternative (unproven) therapies: cranberry
suggested but shorter courses (5-10 days) condition. juice concentrate, probiotics (oral or
likely adequate vaginal), D-mannose, Coleus forskohlii (herb),
• Antibiotic therapy is adjusted based on in PEARLS & CONSIDERATIONS antiseptic instillation (e.g., Tricide-Neo)
vitro susceptibility results while considering
cost-effectiveness, potential adverse reactions, Comments Technician Tips
and the likelihood of developing resistance. • Any bacterial cystitis in a male dog should • When collecting midstream sample for
Fluoroquinolones are often useful for com- be viewed as a complicated infection with urinalysis, first clip long hair and clean
plicated infection. Enrofloxacin 5-20 mg/kg potential for prostatic involvement. perineum.
PO q 24h (dogs); pradofloxacin 3-5 (tablet) • Struvite crystalluria in dogs is most com- • Urine culture is best collected by cystocentesis
or 5-7.5 (suspension) mg/kg PO q 24h (cats) monly due to bacterial UTI or delayed unless bleeding disorder or bladder neoplasia
• Multidrug-resistant E. coli infections may microscopic examination of the sediment is suspected.
be encountered in complicated or persistent and virtually never is related to diet.
infections. Susceptibility may be limited to • Lower urinary tract signs in cats are seldom Client Education
expensive, potentially toxic, or parenterally caused by bacterial cystitis (<5% of cats age Resolution of signs of dysuria is the most
administered antibiotics. Consultation with 10 years or younger with lower urinary tract important piece of information to assess
specialist in small animal internal medicine, signs), making empirical antibiotic therapy effective therapy. Owners should be vigilant
microbiology, or pharmacology is strongly without urine culture inappropriate in cats. in observation of related clinical signs.
recommended: • Concurrent pyelonephritis commonly occurs
○ Nitrofurantoin 4.4-5 mg/kg PO q 8h in the absence of classic signs such as lumbar SUGGESTED READING
○ Amikacin 15-30 mg/kg SQ (or IV, IM) pain, intermittent fever, or neutrophilia. The Olin SJ, et al: Urinary tract infections: treatment/
q 24h or gentamicin 2-6 mg/kg SQ (or absence of these signs in a patient with recur- comparative therapeutics. Vet Clin North Am Small
IV, IM) q 24h rent bacterial cystitis should not defer an Anim Pract 45:721-746, 2015.
Nephrotoxic evaluation for pyelonephritis (e.g., abdominal
■ AUTHOR & EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
Avoid use in dehydrated animals or ultrasound) when pyelonephritis is otherwise
■
those with compromised renal function. suspected (e.g., azotemia).

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