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

This study investigated the role of two drugs, flunixin and phenylbutazone, in preventing the disruption of bowel movement caused by endotoxins in horses undergoing surgery, and found that phenylbutazone was more effective in preserving gastrointestinal motility, while flunixin had a slight advantage in terms of countering cardiovascular side-effects.

Research Background

• The study focuses on post-operative complications in horses, specifically post-operative ileus, which is a serious problem affecting equine motility after abdominal surgery.
• Researchers suggest endotoxin, a toxin present inside bacterial cells that is released when the cell disintegrates, plays a substantial role in the incidence of this complication.

Study Design and Execution

• The researchers looked at the effects of two drugs: flunixin (administered at 1.1 mg/kg bodyweight) and phenylbutazone (given at 4.4 mg/kg bodyweight).
• Both were administered intravenously before exposure to an endotoxin (0.1 microgram/kg bodyweight) to horses equipped with gastrointestinal strain gauges – devices that measure the absolute or relative change in length of an object on which they are mounted.
• The team then measured changes in the gastric, small intestinal, and large intestinal motility.

Research Findings

• Both flunixin and phenylbutazone significantly protected against the disruption in gastrointestinal motility induced by the endotoxin.
• Phenylbutazone was found to be more effective than flunixin in the preservation of motility, particularly in the stomach and left dorsal colon, a significant difference at a statistical level of P < 0.01.
• Both drugs also mitigated the systemic side-effects of the endotoxin. Flunixin was slightly more efficient than phenylbutazone in counteracting the endotoxin’s cardiovascular impacts.

Conclusions and Implications

• The researchers concluded that the negative effects of endotoxins on bowel motility are at least partially mediated by a cyclooxygenase-dependent pathway – a process that involves enzymes converting arachidonic acid to prostaglandins, fundamental mediators of inflammation.
• The study suggests that flunixin and phenylbutazone present unique benefits, with the former demonstrating selectivity for cardiovascular effects and the latter for gastrointestinal effects. Hence, these medicines could be administered based on the specific needs of the equine patient.
• Phenylbutazone would be particularly beneficial in acute colic cases where balancing the mitigation of endotoxin’s disruptive effects on bowel motility and preserving cardiovascular responses indicating surgery is necessary.