Effect of nonsteroidal anti-inflammatory drugs with varied cyclooxygenase-2 selectivity on cyclooxygenase protein and prostanoid concentrations in pyloric and duodenal mucosa of dogs

Objective-To assess in vivo effects of short-term administration of NSAIDs with varied cyclooxygenase (COX)-2 selectivity on pyloric and duodenal mucosa. Animals-8 healthy dogs. Procedures-Each dog received deracoxib (2 mg/kg, PO, q 24 h for 3 days), firocoxib (5 mg/kg, PO, q 24 h for 3 days), meloxicam (0.2 mg/kg, PO, q 24 h for 1 day followed by 0.1 mg/kg, PO, q 24 h for 2 days), or placebo orally for 3 days; there was a 4-week interval between successive treatments. Prior to and on day 3 of drug administration, pyloric and duodenal mucosae were assessed endoscopically and biopsy specimens obtained for histologic examination. Cyclooxygenase-1 and -2 protein expressions were assessed (western blotting) and prostanoid concentrations measured (ELISAs). Data were analyzed by use of an ANOVA. Results-Drug administration did not significantly affect endoscopic mucosal scores, histologic scores, or COX-1 or -2 protein expression. The COX-1 protein expression was significantly higher in the pylorus than in the duodenum. Total prostaglandin and thromboxane B-2 (TXB2) concentrations were significantly greater in pyloric than in duodenal mucosa. Drug administration had no effect on prostaglandin or TXB2 concentrations. Conclusions and Clinical Relevance-Prostanoid concentrations in gastric and duodenal tissues, and gross and histologic appearances, were not significantly affected by drugs with varied COX-2 selectivity. These findings suggested that, for these experimental conditions, there were no differences among the preferential and selective COX-2 inhibitors with regard to adverse effects on the gastric and duodenal portions of the gastrointestinal tract of dogs. (Am J Vet Res 2009;70:1243-1249)