Fluoroquinolone levels in healthy dog urine following a 20-mg/kg oral dose of enrofloxacin exceed mutant prevention concentration targets against Escherichia coli isolated from canine urinary tract infections.

A 3-day course of oral enrofloxacin is effective for treating uncomplicated urinary tract infection (UTI) in dogs when administered 20 mg/kg Q24H. However, emergence of fluoroquinolone-resistant mutants of uropathogens is a concern. Urine concentrations of enrofloxacin and ciprofloxacin were measured in six healthy dogs following dose of enrofloxacin 20 mg/kg. Mutant prevention concentrations of Escherichia coli isolated from canine UTI were also determined against ciprofloxacin. Urine AUC(24)/MPC ratios considering ciprofloxacin concentrations ranged 3819-7767, indicating that selection of resistant E. coli mutants in dogs with uncomplicated UTIs is unlikely in the bladder given that an AUC(24)/MPC = 39 is considered to be protective against mutant selection for ciprofloxacin. However, additional studies are required to evaluate the effects of this enrofloxacin treatment protocol on bacteria that colonize anatomic sites where fluoroquinolones achieve lower concentrations compared to the urinary bladder.

Evaluation of the efficacy and safety of high dose short duration enrofloxacin treatment regimen for uncomplicated urinary tract infections in dogs.

BACKGROUND: Uncomplicated urinary tract infections (UTI) in dogs usually are treated with antimicrobial drugs for 10-14 days. Shorter duration antimicrobial regimens have been evaluated in human patients. HYPOTHESIS: A high dose short duration (HDSD) enrofloxacin protocol administered to dogs with uncomplicated UTI will not be inferior to a 14-day treatment regimen with amoxicillin-clavulanic acid. ANIMALS: Client-owned adult, otherwise healthy dogs with aerobic bacterial urine culture yielding ≥ 10(3) CFU/mL of bacteria after cystocentesis. METHODS: Prospective, multicenter, controlled, randomized blinded clinical trial. Enrolled dogs were randomized to group 1 (enrofloxacin 18-20 mg/kg PO q24h for 3 days) or group 2 (amoxicillin-clavulanic acid 13.75-25 mg/kg PO q12h for 14 days). Urine cultures were obtained at days 0, 10, and 21. Microbiologic and clinical cure rates were evaluated 7 days after antimicrobial treatment was discontinued. Lower urinary tract signs and adverse events also were recorded. RESULTS: There were 35 dogs in group 1 and 33 in group 2. The microbiologic cure rate was 77.1 and 81.2% for groups 1 and 2, respectively. The clinical cure rate was 88.6 and 87.9% for groups 1 and 2, respectively. Cure rates between groups did not differ according to the selected margin of noninferiority. CONCLUSIONS AND CLINICAL IMPORTANCE: HDSD enrofloxacin treatment was not inferior to a conventional amoxicillin-clavulanic acid protocol for the treatment of uncomplicated bacterial UTI in dogs. Further research is warranted to determine if this protocol will positively impact owner compliance and decrease the emergence of antimicrobial resistance.