Dose Titration of the Clinical Efficacy of Intravenous Flunixin Meglumine in a Reversible Model of Equine Foot Lameness

We compared the clinical efficacy of various dosages of flunixin meglumine (FM) with a negative control. FM administration affected dependent variables in a dose-dependent manner, with half-dose FM clinically effective for a shorter period. Higher dosages did not perform differently from one another.

1. Introduction

The objective of this experiment was to compare the clinical efficacy of various dosages of flunixin meglumine (FM) with a negative control. The hypothesis was that higher FM doses would result in improved efficacy in a dose-dependent manner when tested in a reversible model of foot lameness.

2. Materials and Methods

Five Thoroughbreds and five Quarter Horses were shod with adjustable heart bar shoes on one front foot. Weekly grade 4.0/5.0 lameness was induced by tightening a set screw against the heart bar. One hour after lameness induction, treatments were administered intravenously in a randomized order: negative control (isotonic saline: SAL) or FM at 0.55 (half-dose), 1.1 (single dose), or 2.2 (double dose) mg/kg. Results were compared using repeated-measures ANOVA and Student-Newman-Keuls test, with the level of significance set at P < 0.05. 

3. Results

Compared with SAL, half-dose FM reduced heart rate (HR) at 2.33, 2.67, 4.0 to 8.0, and 10.0 hours after administration (P < 0.05). Single-dose and double-dose FM reduced HR from 0.67 to 12.0 hours (P < 0.05). Half-dose FM reduced lameness score (LS) at 1.33 to 12.0 hours, whereas single-dose and double-dose FM reduced LS from 1.0 to 12.0 hours (P < 0.05). Compared with halfdose FM, single- and double-dose LS were further decreased from 1.67 to 12.0 hours (P < 0.05). Mean (±SE) peak plasma concentrations for halfdoses, single doses, and double doses were 6.3 ± 0.4 μg/mL (range, 3.7 to 8.1), 13.1 ± 0.5 μg/mL (range, 10.5 to 15.7), and 28.8 ± 0.9 μg/mL (range, 23.9 to 32.4), respectively.

4. Conclusions

FM administration affected dependent variables in a dose-dependent manner, with half-dose FM clinically effective for a shorter period. Higher dosages did not perform differently from one another.