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Kansas State University College of Veterinary Medicine
Mississippi State University College of Veterinary Medicine
Virginia-Maryland Regional College of Veterinary Medicine
Texas A & M University College of Veterinary Medicine.
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This site demonstrates our approach to evidence based antimicrobial dosing. As such, you should expect that features may change and content will increase with time. Although we believe the current information to be accurate, it is NOT complete and should NOT be used as a guide to therapy at this time .
We encourage you to contact us with questions or comments.
Calf Diarrhea Pathogen Information: Coronavirus
Epidemiology: Bovine coronavirus can cause enteric or respiratory infections in both young and adult cattle. Coronavirus is not quite as prevalent as Rotavirus in the United States , but it is still quite common. Like Rotavirus, it is frequently found as a part of a mixed enteric infection with bacteria or cryptosporidia. Calves with diarrhea due to coronovirus infection tend to be a bit older than calves with E. coli or rotaviral infections; typically affected calves are from 7 days up to 3 weeks of age. Coronaviral disease is more common in the winter months, as the virus persists in cool, humid weather. Coronavirus also causes “winter dysentery” in adult cattle. Asymptomatic coronaviral infection is common in adult cows. These subclinically infected cows will shed the virus in their feces, particularly around the time of parturition and in the winter months. Coronavirus can also reproduce in the upper respiratory tract, and both respiratory and gastrointestinal infections can persist subclinically or infect an animal recurrently. Wild ruminants may harbor coronavirus infection and transmit it to cattle.
Zoonotic Risk: Bovine coronaviruses are not infective to humans.
Clinical features/Specifics of therapy: Diarrhea due to coronavirus may be acute, severe and long lasting. The virus destroys mucosal cells in the large and small intestines, resulting in malabsorbtion, maldigestion, and inflammation. Peak age for occurrence of coronaviral enteritis in calves is 5 to 21 days. Diarrhea is profuse, watery and commonly mucoid in character, and will last for several days as the gut regenerates damaged epithelium. Non-specific signs of dehydration and depression are present. Outbreaks will commonly be explosive, with morbitity rates of 50% or more. Combined infections of coronavirus with another diarrhea-causing agent are common and may be particularly severe, resulting in case fatality rates greater than 50%. Diarrheic disease due to coronavirus may be preceded by mild respiratory disease.
There is no specific therapy for coronavirus, but the disease can be quite severe and supportive therapy is warranted.
Diagnosis/ Necropsy findings/ Sampling goals: Diagnostic labs can isolate coronovirus particles from the feces of affected calves using an ELISA test. Viruses can disappear from the feces quickly, so samples from acute cases are more likely to yield a positive test than samples from chronically ill animals.
Necropsy findings are non-specific and include dehydration and fluid-filled intestines. Samples of all segments of the intestinal tract may be submitted for histopathology, and the contents of colon, ileum and jejunum may be submitted for virus isolation.
Specific prevention measures/ Vaccination: Standard management and hygiene measures should be taken to help control coronavirus infection. It is especially important to isolate calves with diarrhea, as they shed high numbers of coronavirus particles in their feces. As with rotavirus, the best protection against infection is provided by the presence of anti-coronaviral antibodies in the gut lumen of the calf, with serum antibodies being less protective. Within a few days after calving, a beef cow ceases to produce antibody-rich colostrum. On a dairy, colostrum feeding of calves is replaced within a day or two by whole milk or milk replacer feeding. Therefore vaccination of the cow has been of limited benefit, as it only provides significant additional protection to the calf during the short colostrum-feeding period.
Also as with rotavirus, feeding of colostrum or milk products from hyperimmunized cows for the first 30 days of life has been shown to be beneficial in reducing coronaviral diarrhea in calves.