Marbofloxacin is one of the fluoroquinolones developed exclusively for veterinary medicine. The primary aim of the present study is to identify and assess evidence for marbofloxacin's clinical efficacy in the treatment of urinary tract infections in small animal practice. The study included 118 dogs and 123 cats that were referred to the Internal Medicine Department with lower urinary tract symptoms. We excluded animals that had received antimicrobial or anti-inflammatory therapy in the previous 15 days. Diagnosis was confirmed by clinical findings, urinalysis, and imaging. Rectal temperature, appetite, urinary signs, and abdominal pain were monitored during two visits (day 0 and 14). The timetable depended on the diagnosis of the following: two urinalyses, two bacterial examinations, and antibacterial susceptibility testing were performed for each case. Bacterial UTI were confirmed in 36 dogs and 28 cats. Urine samples were collected on day 0, which demonstrated the presence of various bacteria, with a marked predominance of P. mirabilis and coagulase-positive Staphylococci in canine and feline urine samples, respectively. Antimicrobial susceptibility test results revealed 25 (65.7%) of dog isolates and 24 (85.7%) of cat isolates were susceptible to marbofloxacin. Treatment of UTIs is generally challenging for the small animal practitioner. Because of the need for long-term antimicrobials, bacterial culture and susceptibility tests are especially important for successful treatment. Marbofloxacin can be part of an effective treatment of UTIs in dogs and cats.