A case of viral neonatal calf diarrhea in a Quebec dairy herd.

This report is concerned with a consistent problem of neonatal calf diarrhea (NCD) in a dairy herd in which, for nearly two years, the morbidity had approached 100% and the mortality had varied from 20% to 45%. Generally, diarrhea appeared at three days of age. By the fluorescent antibody tissue section technique the two Nebraska NCD viruses (reo-like and corona-like) were detected in the cytoplasm of many absorptive cells of the small intestine from a calf submitted for necropsy. Reo-like virus antigen was not detected in the absorptive and crypt cells of the colon but coronavirus-like antigen was. An adenovirus was also isolated from the small intestine of this calf. The disease was reproduced experimentally in a two day old colostrum deprived calf with a bacteria free intestinal homogenate obtained from the naturally infected calf. Both Nebraska NCD viruses were demonstrated in this experimental animal. However, the adenovirus was not re-isolated. Histological lesions observed in the small and large intestines of the naturally and experimentally infected calves were similar and because of their good correlation with the immunofluorescent findings, a combination of the two Nebraska NCD viruses was thought to be a major cause of the neonatal calf diarrhea problem afflicting this dairy herd.