Diarrhea in Neonatal Calves

Adapted by Dr. Pat Blanchard, DVM, PhD, California Animal Health and Food Safety Laboratory, Tulare Branch

Diarrhea in calves under 30 days old is caused by a variety of agents, some of which are age specific or require tissue examination to detect. The most common pathogens found in calves are parasites (cryptosporidia), viruses (rotavirus, coronavirus) and bacteria (Salmonella, K99 E. coli and attaching and effacing E.coli - AEEC).  All except AEEC can be detected in the feces from live, sick calves. However colon tissue from dead calves improves detection of coronavirus and is required to detect AEEC. Salmonella, AEEC, and coronavirus in calves can cause bloody diarrhea. Calves with systemic bacterial infections (i.e. E. coli, Salmonella) or pneumonia may also experience diarrhea even though no infectious agents are present in their intestine. Rumenitis from milk fermenting in the rumen or bacteria, yeast and other fungi growing in the rumen and abomasum can cause decreased appetite or stomach pain in calves.

Parasites like cryptosporidia are not shed for at least 4 days in the feces so testing calves younger than 4 days old for this parasite is not useful. Coccidia have a prepatent (pre-shedding) period of 15-21 days and we have not seen this organism in calf hutch raised calves though it might occur in pasture or group housed calves.

K99 E. coli can cause high death losses and very rapid dehydration in calves, but typically only affects calves less than 6 days old, most often 2-3 days of age. There are effective dry cow vaccines for K99 E. coli, but they must contain the K99 component.

When mortality associated with calf diarrhea increases, this usually means multiple infectious agents are present which causes more severe disease. Freshly dead or moribund (near death) calves or tissues from these calves taken at a field necropsy are the best samples to submit to the California Animal Health and Food Safety Laboratory to diagnose the causes. The selected calves should have been sick less than 4 days and not been treated with antibiotics. If a high percent of calves become sick but very few die, sentinel bull calves that are exposed to the same conditions as the heifer calves could be submitted when they become ill to help identify the problem affecting the heifer calves. If the dairy is having a problem of poor doers after calves recover from diarrhea, this may indicate a rumen or abomasal problem secondary to intensive treatment.

Link to News Article (PDF): Neonatal Calf Diarrhea