Antagonism of endotoxin‐induced disruption of equine bowel motility by flunixin and phenylbutazone

Abstract

Summary Post operative ileus is a serious complication of abdominal surgery in horses and there is evidence that endotoxin plays a significant role in its pathogenesis. Pre‐treatment with intravenous (iv) flunixin (1.1 mg/kg bodyweight [bwt]) or phenylbutazone (4.4 mg/kg bwt) significantly antagonised the acute disruption of gastric, small intestinal and large intestinal motility induced by 0.1 μg/kg bwt iv endotoxin in ponies implanted with gastrointestinal strain gauges. Phenylbutazone was more effective than flunixin and this was significant (P<0.01) for the stomach and left dorsal colon. Both drugs reduced the acute systemic side‐effects of the endotoxin and flunixin was slightly more effective than phenylbutazone in antagonising the cardiovascular effects. These results suggest that the acute effects of endotoxin on bowel motility are mediated at least in part by a cyclooxygenase dependant pathway. Flunixin and phenylbutazone showed a relative selectivity for the cardiovascular and gastrointestinal effects of endotoxin, respectively. Phenylbutazone may be of use clinically in acute colic cases, antagonising the disruptive effects of endotoxin on bowel motility, without entirely blocking the cardiovascular effects which can indicate that the patient has a condition requiring surgery.

The use of multimodal analgesia in the management of suspected extremity compartment syndrome in the pelvic limb of a horse

“…). Flunixin is more likely to mask the cardiovascular changes associated with endotoxaemia, should this develop as a consequence, potentially delaying identification and appropriate intervention (King and Gerring ; Mair and Edwards ). Newer NSAIDs such as firocoxib could have been considered due to demonstrable efficacy in reducing musculoskeletal pain and potentially improved safety profile with higher cyclo‐oxygenase‐2 (COX‐2) selectivity (Koene et al .…”

An update on equine post‐operative ileus: Definitions, pathophysiology and management

“…The relative merits of each remain unclear. Those NSAIDs are believed to have a beneficial effect on the acute systemic side effects of endotoxins, including the deterioration in cardiovascular parameters [134]. Indeed, no studies have been performed in horses showing NSAIDs reduce the incidence of POI; however, studies have been performed showing the effects of flunixin meglumine and phenylbutazone on GI motility in horses with abdominal pain and inflammation.…”

Interactions between erythromycin, flunixin meglumine, levamisole and plant secondary metabolites towards bovine gastrointestinal motility—in vitro study

“…Erythromycin is a motilin receptor agonist with a profound effect on gastroduodenal motor activity (Catnach & Fairclough, ). Flunixin meglumine changes bowel motility patterns through the modulation of prostaglandin synthesis (King & Gerring, ). Levamisole exhibits nicotine‐like activity (Rew, ; Hsu, ).…”