A Comparative Pharmacokinetic Analysis of Oral and Subcutaneous Meloxicam Administered to Postpartum Dairy Cows

The dairy industry needs evidence-based solutions to mitigate painful procedures and conditions in dairy cattle. The objective of this study was to compare the pharmacokinetic properties of orally versus subcutaneously administered meloxicam in early-lactation dairy cattle. The study was conducted at a commercial dairy herd in southwestern Ontario, Canada. Twelve postpartum cows were enrolled in the study, receiving either subcutaneous meloxicam (MET) at 0.5 mg/kg body weight (n = 6) or oral meloxicam (MOS) at a higher dose of 1.0 mg/kg body weight (n = 6) immediately following parturition. The predicted half-life (12.5 ± 2.0 vs. 28.5 ± 2.0 h), C_max (1.59 ± 0.15 vs. 1.95 ± 0.16 μg/mL), T_max (5.33 vs. 11.7 h), and AUC_0→∞ (39.6 ± 7.4 vs. 115.6 ± 19 h * µg/mL) differed significantly between MET and MOS cows, respectively. After controlling for the treatment group, first lactation cows had a significantly higher half-life (4.1 ± 2.1 h), C_max (0.56 ± 0.2 µg/mL), and AUC_0→∞ (21.6 ± h * µg/mL) relative to second lactation or greater cows, respectively. Administration of meloxicam through the subcutaneous or oral route results in appreciable, dose-dependent systemic levels.