Pharmacokinetics of multiple doses of chloramphenicol in fed adult horses

•There was marked inter-individual variation in serum chloramphenicol concentrations after oral dosing in adult horses.•Average serum concentrations of chloramphenicol were below recommended susceptibility breakpoints for bacteria.•Time above 4 or 8 μg/mL, the susceptibility breakpoints for bacteria, was much less than 50% of the dosing interval.•When chloramphenicol is administered orally at a dose of 50 mg/kg q6 h, bacteria with an MIC of ≤2 μg/mL should be targeted.