The present randomized, controlled, blinded clinical trial compared the efficacy of high-dose short-duration (HDSD) enrofloxacin treatment with a conventional 14-day course of amoxicillin-clavulanic acid in treating uncomplicated canine urinary tract infections (UTIs). Adult dogs (n = 68) with clinical and microbiological evidence of UTI were randomly assigned to 2 study groups. Group 1 (n = 35) received enrofloxacin 18–20 mg/kg PO q24h for 3 days. Group 2 (n = 33) received amoxicillin-clavulanic acid 13.75–25 mg/kg q24h for 14 days. Urine cultures were obtained and clinical signs and adverse events recorded on day 0 and day 10 (group 1) or day 21 (group 2). Long-term clinical and microbiological cure was also determined at day 21 (group 1 only). Results found microbiologic cure rate was 77.1% and 81.2% for groups 1 and 2, respectively. Clinical cure rate was 88.6% and 87.9%, respectively. Differences between cure rates were not statistically significant, indicating that HDSD treatment with enrofloxacin is not inferior to conventional 14-day amoxicillin-clavulanic acid for uncomplicated canine UTIs. HDSD was well tolerated. HDSD enrofloxacin can be considered as an alternative treatment in uncomplicated canine UTIs. Further research on compliance and antimicrobial-resistance is needed.

In humans with uncomplicated UTI, short treatment duration and decreased dosing frequency of antimicrobials have been reported to increase compliance, lower costs, decrease adverse effects, and may be as effective as conventional, longer term protocols. To date, the efficacy of a HDSD antimicrobial regimen in naturally occurring, uncomplicated UTI in dogs has not been evaluated.

In this study, HDSD enrofloxacin treatment was not inferior to a conventional 14-day amoxicillin-clavulanic acid for uncomplicated bacterial UTI in dogs. Additional studies will be necessary for guidelines on protocols. It is possible that shortened dosing protocols will positively impact compliance; however, questions remain about adverse effects and antimicrobial resistance. Antimicrobial resistance of canine uropathogens to fluoroquinolones has been reported, and it is unknown what impact this will have on selection for antimicrobial-resistant bacteria.—Gregory F. Grauer, DVM, MS, DACVIM (Small Animal)

Evaluation of the efficacy and safety of high dose short duration enrofloxacin treatment regimen for uncomplicated urinary tract infection in dogs. Westropp JL, Sykes JE, Irom S, et al. J Vet Intern Med 26:506-512, 2012.