FIROCOXIB EFFICIENCY ON LIPOPOLYSACCHARIDE-INDUCED ARTHRITIS IN HORSES

Abstract

Lameness is a highly prevalent condition in horses and the principal cause of removal from athletic activity. Synovitis or arthritis in horses is frequently treated by administration of non-steroidal inflammatory drugs (NSAIDs) which inhibit cyclooxygenase isoforms (COX -1 and COX-2). Constitutively expressed COX-1 is involved in physiologic functions, such as the maintenance of gastric mucosa integrity, whereas COX-2 generates inflammatory prostaglandins at sites of inflammation. Selective cyclooxygenase-2 inhibitors were designed based on the hypothesis that selective inhibition on the COX-2 isoform should reduce pain and inflammation without compromising the integrity of the gastric mucosa. The objective of the present study is to compare the anti-inflammatory effects of the preferential non-selective COX inhibitor phenylbutazone with the preferential COX-2 inhibitor firocoxib in horses with lipopolysacharide (LPS) - induced arthritis. Two groups of horses (n=6) will receive phenylbutazone (4mg/kg) or firocoxib (0,1mg/kg) orally daily, 2 hours following injection of LPS into the metacarpophalangeal joint. The effectiveness of the drugs will be assessed through clinical evaluation, termografic and ultrassonografic examination, synovial fluid and locomotion analysis. A minimum criterion of 5% will be adopted for statistical significance.