[Physiological function of the gastrointestinal tract and pathophysiological changes in neonatal diarrhea of calves]

Firstly, the basic principles of absorption and secretion in the intestine of healthy animals are described. The etiology and the pathophysiologic mechanisms of neonatal diarrhea in the calf due to E. coli and rota-/coronavirus are discussed. Enterotoxins of E. coli stimulate primarily the secretion of chloride (and thereby water) in the small intestine without damaging the intestinal mucosa. The sodium-dependent transport systems for the absorption of glucose and amino acids remain intact. In contrast, infections with rota- or coronavirus lead primarily to a disturbance of absorption processes in the intestine due to villous atrophy. Crypt cells are indirectly affected by inflammation mediators. Intestinal motility is inhibited during most diarrheic episodes; the application of para-sympatholytics in therefore not favourable.