Pathological changes in the small intestine of neonatal calves with enteric colibacillosis.

Three neonatal calves, protected from colisepticaemia by intravenously administered immunoglobulin M, were infected orally with Escherichia coli type 0101 K?(A). All calves developed severe enteric colibacillosis. When they were 4 days old stunting and fusion of villi were seen in the distal half of the small intestine and were associated with adhesion of the challenge organism to the mucosa. Two uninfected control calves kept under similar conditions, did not develop diarrhoea and had no lesions.