How often dogs have positive urine cultures with inactive urine

Abstract

BACKGROUND: Urinalysis (UA) is often used to screen for bacterial cystitis, regardless of sediment results, and followed up by quantitative urine culture (UC) for definitive diagnosis. OBJECTIVES: Determine prevalence of positive UCs in dogs with inactive urine sediments on routine UA. ANIMALS: A total of 1049 urine samples with inactive urine sediments and UCs collected from dogs presented to a veterinary specialty hospital between January 2018 and February 2020. METHODS: Retrospective study of dogs with an inactive urine sediment on routine UA and follow-up UCs. Signalment, UA findings, proteinuria, and UC results were recorded. Associations among these findings were assessed using multivariate logistic regression carried out using a backward stepwise method. RESULTS: Overall prevalence of positive UC was 3.4% (95% confidence interval [CI], 2.4-4.8). Escherichia coli was the most commonly isolated bacteria. Only naturally voided samples were associated with increased prevalence of positive culture when compared to collection by cystocentesis or a non-specified method. No statistically significant association with culture positivity was found for urine protein-to-creatinine ratio, urine specific gravity, urine pH, breed, age, or sex. CONCLUSIONS AND CLINICAL IMPORTANCE: Based on the low prevalence (3.4%) of positive culture in urine samples from dogs with inactive sediment on routine UA and the relatively high cost of UC and sensitivity, cost-benefit analysis including clinical suspicion of lower urinary tract disease should inform testing decisions, rather than routinely performing cultures on urine samples without active sediments.