Experimental inoculation of foals and pigs with an enterotoxigenic E. coli isolated from a foal.

Hemolytic E. coli strain 807-13, O149:NM:K88(STb+, LT+), was isolated from the feces of a neonatal diarrheic foal. E. coli 807-13 was examined for adhesion to brush border membranes (BBM) from foals, adult horses and pigs, and its pathogenicity was assessed in neonatal foals and pigs. E. coli 807-13 did not adhere to equine BBM but adhered to pig BBM. It did not cause diarrhea nor did it colonize the intestinal epithelium of 3 colostrum-deprived and 3 suckled foals challenged at 24 h of age. Acute ulcerative gastritis and acute suppurative gastritis were observed in 2 colostrum-deprived challenged foals, and acute neutrophilic enteritis was observed in 1 colostrum-deprived and in 1 suckled challenged foal. No similar histopathologic lesions were detected in the control foals. Both gnotobiotic and suckled pigs developed diarrhea after challenge exposure to E. coli 807-13 and the intestinal epithelium of the pigs was colonized. Histopathologic evidence of gastritis and enteritis among the foals indicated some complicity of E. coli 807-13 in foal enteric disease.