Neonatal diarrhea in calves, goats and lambs is caused by a variety of agents, some of which are age specific or require histopathology to diagnose.
Coronavirus is usually diagnosed by fluorescent antibody testing (FAT) of colon tissue but electron microscopy (EM) and ELISA can also be used to detect this virus but are not as sensitive as FAT. Septic animals may have diarrhea though no enteric pathogens are present.
Samples from field necropsies should include fresh lung, liver, ileum, spiral colon and feces (5ml). Fixed tissue minimally should include two loops of spiral colon, ileum, jejunum, abomasum, rumen, lung, liver and any gross lesions. Additional tissues that are helpful are kidney, spleen, thymus, heart and adrenal gland.
This information was reprinted with permission from the California Animal Health and Food Safety Laboratory System’s January 2012 CAHFS Connection.
+attachment sites for K99 E. coli are lost after 5 days of age when the intestine epithelium matures.
*cryptosporidia are not shed in feces before 4 days of age but may be seen earlier by histopathology.
**coccidia pre-patent period is 21 days. CAHFS does not usually see it in hutch calves though it might be seen as early as 3 weeks in calves, kids and lambs on pasture or in group pen housing.