Coronaviral enteritis of young calves: virologic and pathologic findings in naturally occurring infections.

Coronavirus was detected in 113 (16.4%) of 689 calf enteric disease accessions received at the South Dakota Animal Disease Research and Diagnostic Laboratory from Mar 1, 1975 to Oct 31, 1976. During this period, modified live coronaviral vaccine was not in common use in this area. The virus was detected by negative stain electron microscopy of feces and intestinal contents and by fluorescent antibody examination of intestine and colon sections. Calves with coronaviral enteritis ranged in age from 1 day to 3 months, with most cases occurring between 1 and 7 days. At necropsy, a green, mucoid fecal cast was commonly seen in the colon. Histopathologic examination revealed necrotizing enterocolitis.