Oral Administration of Meloxicam and Flunixin Meglumine Have Similar Analgesic Effects After Lipopolysaccharide-Induced Inflammatory Response in Thoroughbred Horses.

Flunixin meglumine (FM), a nonselective cyclooxygenase (COX) inhibitor, is most frequently selected for the treatment of equine systemic inflammatory response syndrome (SIRS)/endotoxemia. However, FM has considerable adverse effects on gastrointestinal function. The aims of this study were to compare the effect of meloxicam (MX), a COX-2 selective inhibitor commonly used in equine clinical practice, with FM, and to investigate the potential for clinical application in horses with SIRS/endotoxemia. Fifteen horses were divided into three groups of five and orally administered MX (0.6 mg/kg), FM (1.1 mg/kg), or saline as placebo at 30 minutes after LPS challenge. Clinical parameters, including behavioral pain scores, were recorded and blood for clinical pathological data was collected at various times from 60 minutes before to 420 minutes after LPS infusion. The pain score were significantly lower in both the MX and FM groups than in the placebo group, with no significant difference between them. Body temperature was significantly lower in the MX and FM groups than in the placebo group. Heart rates and respiratory rates, hoof wall surface temperature, and leukocyte counts changed similarly between the MX and FM groups. TNF-α and cortisol were lower in the FM group than in the MX group. The results suggest that MX suppresses the inflammatory response after LPS infusion and has an analgesic effect similar to that of FM. Given the adverse effects of nonselective COX inhibitors, clinical application of MX may be beneficial in horses with SIRS/endotoxemia.