Enrofloxacin-d5 is a deuterated internal standard for Enrofloxacin, used in quantitative LC-MS/MS analysis for pharmacokinetic studies. Its parent compound, Enrofloxacin (BAY-Vp-2674), is a fluoroquinolone antibiotic effective against Mycoplasma bovis with a reported MIC90 of 0.312 µg/mL, applicable in both in vitro and animal infection model research.