A fluoroquinolone antibiotic; inhibits the growth of Gram-positive and Gram-negative bacteria (MICs = 4 and 1 μg/ml for S. aureus and P. aeruginosa, respectively); inhibits the growth S. pseudintermedius, S. aureus, E. coli, Pasturella, and S. canis isolates from dogs (mean MIC50s = 0.25, 1, 0.03, 1, and 1 μg/ml, respectively); topical administration reduces corneal ulcer size in a rabbit model of P. aeruginosa corneal infection at 0.1 % v/v; prevents encrusted cystitis in bladder and increases survival in a rat model of Corynebacterium group D2 infection at 80 mg/kg/day