The effects of cyclo-oxygenase inhibitors on bile-injured and normal equine colon.
Authors: Campbell N B, Jones S L, Blikslager A T
Journal: Equine veterinary journal
Summary
# Editorial Summary: COX Inhibitors and Equine Colonic Injury Recovery of equine colon from bile-induced damage appears independent of prostaglandin production, yet nonselective COX inhibitors may compromise mucosal barrier function in healthy tissue—findings that carry important implications for clinical NSAID use in horses prone to colitis. Campbell and colleagues used an ex vivo Ussing chamber model to expose pelvic flexure segments to deoxycholate (mimicking bile injury) followed by a 4-hour recovery period, comparing responses to flunixin (nonselective COX inhibitor) and etodolac (selective COX-2 inhibitor). Contrary to their hypothesis, both drugs similarly failed to impair recovery of the injured mucosa despite significantly suppressing prostanoid synthesis, but flunixin notably increased permeability in undamaged control tissue whilst etodolac did not. These results suggest that whilst COX-derived prostanoids may not be essential for mucosal repair after acute bile injury, nonselective COX inhibition carries a distinct risk of barrier dysfunction in normal colon—a distinction that could inform drug selection for horses requiring analgesia during gastrointestinal compromise or those with a history of colitis.
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Practical Takeaways
- •Selective COX-2 inhibitors (e.g. etodolac) may be safer than nonselective NSAIDs for horses with colonic disease or at risk of colitis, as they preserve COX-1 activity without increasing mucosal permeability
- •Nonselective COX inhibitors like flunixin can increase intestinal permeability in normal tissue, which may predispose to colitis in susceptible horses
- •While NSAID use does not directly impair colonic repair after bile injury, the increased permeability with nonselective inhibitors warrants careful patient selection and monitoring
Key Findings
- •Recovery of bile-injured colonic mucosa was unaffected by flunixin or etodolac despite significantly depressed prostanoid production
- •Flunixin treatment of control tissue increased mucosal permeability significantly, whereas etodolac had no significant effect
- •COX-elaborated prostanoids may not be essential for recovery from bile-induced colonic injury in horses
- •Nonselective COX inhibitors increase permeability in normal equine colon tissue