CANINE MEDICINE
Article reprinted with the permission of Clinician’s Brief. The article was originally printed in December 2012. CB is published by Brief Media.
CB is the official publication of the NAVC. CB provides relevant diagnostic and treatment information for small animal practitioners. All rights reserved.
Canine Urinary Tract
Infections
Gregory F. Grauer, DVM, MS, DACVIM, Kansas State University
Georgia, an 8-year-old spayed black Labrador retriever, was presented with
urinary incontinence of several months’ duration.
History
Georgia’s incontinence, most pronounced when she was
sleeping or lying down, had been present for several months
and preceded more recent signs of lower urinary tract inflammation (ie, pollakiuria, dysuria/stranguria, breaking normal housetraining behavior).
Examination
Georgia was slightly overweight and had excessive perivulvar
skinfolds with some perivulvar inflammation and evidence of
licking and pigmentation change (Figure 1). Physical examination, including rectal examination and palpation of the urinary bladder, was unremarkable.
Initial Laboratory Evaluation
CBC and biochemistry profile were within normal limits.
Urinalysis obtained by cystocentesis revealed a cloudy appearance with pH of 7.5, urine specific gravity of 1.037, 2+
Figure 1. Radiograph of the vulvar region demonstrating recessed vulva
and perivulvar dermatitis
Figure 2. Double-contrast cystogram demonstrating the intra-pelvic
bladder
proteinuria, 25 to 30 RBCs/hpf, 10 to 15 WBCs/hpf,
25 struvite crystals/hpf, and gram-negative rods. Urine
culture yielded Escherichia coli (>1000 cfu/mL) sensitive to amoxicillin–clavulanic acid.
Plain film radiographs of the abdomen followed by
a doublecontrast cystogram demonstrated a intrapelvic bladder (Figure 2).
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ASK YOURSELF?
Is this urinary tract infection simple or complicated?
CORRECT ANSWER Complicated
Simple vs Complicated Urinary Tract Infections
Simple or uncomplicated urinary tract infections
(UTIs) lack structural or functional abnormalities in the
host’s defence mechanisms. This form of infection is
easiest to treat and usually clears soon after appropriate antibiotic treatment. Simple, uncomplicated UTIs
are the most common type to occur in female dogs.
Complicated UTIs are associated with one or more
defects in the host’s defence mechanisms: for example, interference with normal micturition, anatomic
defects, damage to mucosal barriers, or alterations in
urine volume or composition. Health of host defence
mechanisms appears to be most important in influencing the pathogenesis of UTIs. Although antibiotic
treatment is the cornerstone of UTI management,
status of host defence mechanisms is thought to be
the most important determinant of longterm treatment outcome. Antibiotic treatment should control
the pathogenic bacterial growth for a period sufficient
to allow host defence mechanisms to be corrected
and prevent colonisation of the urinary tract without
further antibiotic administration.
Diagnosis
Georgia had a UTI caused or complicated by probable urethral sphincter mechanism incompetence
(USMI), abnormal vulvar anatomy, and subsequent
perivulvar inflammation. The intra-pelvic bladder location results in a shortened urethra, which has been
associated with USMI. Decreased urethral sphincter
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