DRUGS COORDINATING AND RESTORING GASTROINTESTINAL MOTILITY AND THEIR EFFECT ON SELECTED HYPODYNAMIC GASTROINTESTINAL DISORDERS IN HORSES AND CATTLE

Hypodynamic gastrointestinal disorders in horses and cattle that are t hought to benefit from treatment with drugs restoring and coordinating gastrointestinal motility include post-operative ileus and large colo n impaction in the horse and displacement of the abomasum and dilatati on of the cecum in cattle. Important physiologic, pathophysiologic and pharmacologic mechanisms involved in the intrinsic control of gastroi ntestinal motility include cholinergic, adrenergic, dopaminergic, sero toninergic, and opioid-mediated pathways. Preliminary results suggest that cisapride, acting on 5-Hydroxytryptamine receptors, might be usef ul for treatment of idiopathic postoperative ileus and the alpha(2)-ad renoceptor blocking agent yohimbine for endotoxic postoperative ileus. Naloxone, an opioid; antagonist, and neostigmine, an acetylcholineste rase inhibitor, are thought to restore motility of the large colon in cases of large colon impaction in the horse. Bethanechol and neostigmi ne significantly increase myoelectric activity of the cecum and proxim al loop of the ascending colon in healthy cows. Investigations of the effects of prokinetic drugs on displacement of the abomasum of cattle do not allow any conclusions because no results derived from controlle d experimental disease models are available.