COLIC MOTOR COMPLEX OF THE CECUM AND PROXIMAL LOOP OF THE ASCENDING COLON OBSERVED IN AN EXPERIMENTAL COW WITH LARGE INTESTINAL-OBSTRUCTION

Myoelectric activity of the cecum and proximal loop of the ascending c olon (PLAC) and the effect of xylazine on motility of this intestinal segment in an experimental cow with large intestinal obstruction are d escribed and compared with the normal motility pattern. During obstruc tion, three major observations were made in the prestenotic area. (i) Mean spike duration, overall duration of spiking activity (expressed a s percentage of total recording time), number of spikes propagated fro m the cecum towards the obstruction site, and velocity of propagated s pikes were substantially increased. (ii) The spike frequency was in th e physiologic range. (iii) A single injection of xylazine, administere d intravenously at a dose of 0.05 mg/kg markedly reduced the mean spik e duration, the overall spiking activity, and the number of propagated spike sequences, and abolished signs of abdominal discomfort. Our dat a indicate that obstruction of the bovine colon causes a similar patte rn of prestenotic hypermotility (colic motor complex) as described for the small intestine of the horse. Xylazine may be a suitable drug to disrupt prestenotic hypermotility and alleviate abdominal discomfort d uring proximal colonic obstruction in cattle.