Danofloxacin mesylate (CP 76136-27) is a fluoroquinolone antibacterial for veterinary use. Target: Antibacterial Danofloxacin mesylate (CP 76136-27) is a synthetic antibacterial agent of the fluoroquinolone class, acts principally by the inhibition of bacterial DNA-gyrase, which is necessary for supercoiling of DNA to provide a suitable spatial arrangement of DNA within the bacterial cell. The minimum inhibitory concentration of danofloxacin against 90% (MIC90) of contemporary European and North American field isolates of Pasteurella haemolytica, Pasteurella multocida and Haemophilus somnus, the most important bacterial respiratory pathogens of cattle, is 0.125 μg/ml [1]. Danofloxacin mesylate (CP 76136-27) shows protective dose (PD50) of 0.38, 0.8, 2.42 mg/kg for P. multocida, E. coli and S. choleraesuis in in vivo mouse protection assay [2].