Colibacillosis in neonatal lambs: onset of diarrheal disease and isolation and characterization of enterotoxigenic Escherichia coli from enteric and septicemic forms of the disease.

A lamb ligated intestinal segment (LIS) test was adapted to determine the enterotoxigenicity of Escherichia coli isolates obtained from fecal and blood specimens from neonatal lambs with overt diarrheal disease. The lamb LIS was distended by 28 of 80 (37%) isolates from fecal specimens from 23 affected lambs. Enterotoxigenic E coli isolations were made from 10 of the 23 lambs examined. Isolates of E coli were made from the blood of 17 of 76 (22%) animals with severe diarrheal disease. Distention of the lamb LIS was caused by 3 of 39 (7.7%) isolates from 2 of 17 lambs with E coli septicemia. All lambs (n = 266) that were born during a 4-day period in an intensified shed lambing operation and that were not given prophylactic antibiotic therapy developed diarrheal disease within 28 hours of birth. Signs of enteric disease appeared in lambs born during inclement weather in a significantly (P less than 0.001) shorter period than in those born during mild weather conditions.