The role of intestinal motility in the pathogenesis of infectious diarrhea in the neonatal calf

Abstract

Jejunal Thiry-Vella loops in calves, implanted with electrodes, were used to distinguish the effects of infectious agents from the effects of fluid distention on myoelectric activity. Myoelectric activity was recorded in four calves in response to infusion of four treatments: 1) cell culture media filtrate (control); 2) non-absorbable electrolyte solution (ColyteO); 3) E. coli heat-stable enterotoxin (STa); and 4) bovine coronavirus. Myoelectric activity was recorded for four hours following each treatment. Five additional four hour recording sessions were conducted follow ing coronavirus infection. Myoelectric activity was recorded in two additional calves. Two control treatments were administered 48 hours apart and coronavirus immediately followed the second control treatment. In the first four calves, all treatments including control, induced intense spike activity during the first hour. This spike activity was attributed to fluid distention in all treatments. This intense spike activity was further characterized by small spikes and super spike complexes (SSC's). The spiking rate of SSC's was increased in the first hour by colyte infusion, and the percentage of type 1 SSC's was increased following infusion of colyte and Sta. All treatments increased the median duration of the MMC compared to the control treatment. Both STa and coronavirus increased phase 11 activity. The increased duration if the MMC following colyte infusion was due to the initial disruption of the MMC caused by fluid distention. The cause of the increased duration of the MMC and phase 11 activity following STa and coronavirus treatments could not be determined from this study. In the remaining two calves, the duration of the MMC did not change following any of the treatments. These findings suggest that time alone was not the cause of these changes in duration of the MMC's in the first four calves. These results also suggest that changes in myoetectric activity are not induced by early coronavirus infection.