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 colon (PLAC) and the effect of xylazine on motility of this intestinal segment in an experimental cow with large intestinal obstruction are described and compared with the normal motility pattern. During obstruction, three major observations were made in the prestenotic area. (i) Mean spike duration, overall duration of spiking activity (expressed as percentage of total recording time), number of spikes propagated from the cecum towards the obstruction site, and velocity of propagated spikes were substantially increased. (ii) The spike frequency was in the physiologic range. (iii) A single injection of xylazine, administered intravenously at a dose of 0.05 mg/kg markedly reduced the mean spike duration, the overall spiking activity, and the number of propagated spike sequences, and abolished signs of abdominal discomfort. Our data indicate that obstruction of the bovine colon causes a similar pattern 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 during proximal colonic obstruction in cattle.