We determined the pharmacokinetic properties of ceftiofur crystalline-free acid (CCFA), a long-acting antibiotic, after a single intramuscular injection in cattle egrets (Bubulcus ibis). A dose of 20 mg/kg was administered intramuscularly to 18 birds and blood samples were collected via jugular venipuncture at 1, 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, and 240 hours after CCFA administration. Plasma concentrations of ceftiofur free acid equivalents (CFAEs) were measured via high-performance liquid chromatography. The minimum inhibitory concentration (MIC) of 1 μg/mL was reached by 1 hour after administration and remained higher than the MIC for at least 72 hours in all birds. This target concentration is effective for many bacterial infections in avian species. The area under the plasma concentration versus time curve was 451.3 h*μg/mL, maximum plasma concentration was 16.22 μg/mL, time to maximum plasma concentration was 3.2 hours, mean harmonic half-life was 37.92 hours, and time that the concentrations of CFAEs were higher than the target MIC was a minimum of 72 hours.