Tegaserod Enhances Gut Motility in Horses

A recent study conducted at the University of Berne Equine Clinic in Switzerland demonstrated that the prokinetic (promoting movement) drug tegaserod stimulated gut motility and accelerated gastrointestinal transit in healthy horses. The study findings, published in the Equine Veterinary Journal, are consistent with those observed in large clinical trials involving human patients and in studies of other animal species.

According to lead investigator Britta Lippold, DVM, "Our data suggest that tegaserod, given intravenously, might be useful for the treatment of paralytic ileus after colic surgery, or as an adjunct therapy for horses suffering from impaction."

Tegaserod, marketed as Zelnorm by Novartis Pharmaceuticals, was approved by the U.S. Food and Drug Administration in July 2002 for the treatment of irritable bowel syndrome with constipation in humans. "Presently," Lippold noted, "Tegaserod is the only potent serotonin type-4 receptor agonist available in many countries, including the U.S."

Previous laboratory research proved the beneficial actions of the drug on equine gut tissue. When applied to isolated muscle preparations of equine ileum and pelvic flexure, tegaserod induced a significant increase in the frequency and amplitude of contractions. 

To determine its effects on gut motility in normal horses, six healthy, mature horses received tegaserod intravenously twice daily for two days. Prior to drug administration, each horse was given 200 barium-filled spheres via stomach tube. Feces were collected every three hours, and the eliminated spheres were identified radiologically. 

Gut motility of the horses was analyzed in three ways: By determining the intestinal transit time of the barium-filled spheres, by measuring the amount and frequency of defecation, and by scoring gut sounds associated with gastrointestinal activity. 

The results of Lippold's study revealed that tegaserod significantly accelerated the gastrointestinal transit time of the barium filled spheres. Although treated horses exhibited greater frequency of defecation, there was no significant change in fecal consistency. Administration of tegaserod improved scores of gut sounds associated with propulsive intestinal activity.

No adverse side effects were observed during or after administration of the drug at a dose of 0.02 mg/kg body weight. According to Lippold, "Large clinical studies in thousands of human patients have been performed and have demonstrated both the tolerability and the safety of tegaserod." Likewise, the compound was well tolerated by horses, with no measurable ill effects on behavior, body temperature, heart rate, respiratory function, or clinical laboratory data.

Although tegaserod appears promising for the treatment of advanced impaction and paralytic ileus in the equine patient, the drug is not yet sold on the veterinary market. "Thus far," Lippold explained, "tegaserod is only available in tablets for the treatment of functional bowel disorders in humans. The intravenous form of tegaserod used in our study was prepared for experimental purposes only."

About the Author

Rallie McAllister, MD

Rallie McAllister, MD, grew up on a horse farm in Tennessee, and has raised and trained horses all of her life. She now lives in Lexington, Ky., on a horse farm with her husband and three sons. In addition to her practice of emergency and corporate medicine, she is a syndicated columnist (Your Health by Dr. Rallie McAllister), and the author of four health-realted books, including Riding For Life, published by Eclipse Press and available at www.ExclusivelyEquine.com or by calling 800/582-5604.

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