Historically, coronavirus was considered a rare cause of foal diarrhea. It had not been considered a disease that affected adult horses. PCR tests have provided improved methods of detection and, in 2011, this condition was found in stabled adult horses that had colitis. Since then, coronavirus is diagnosed more frequently. Dr. Nicola Pusterla (UC Davis) is on the forefront of research on this condition.

Affected horses usually have a fever, are depressed and have a poor appetite. Manure varies from normal to soft "cowpie", to diarrhea. Occasionally signs of abdominal pain (colic) are present. As of 2013, I have treated several outbreaks in which we have detected this organism.

Coronavirus is probably spread through contact with manure that contains the virus via human handlers and shared equipment.

This disease is fairly mild and self-limiting, meaning that it usually resolves on its own in time. The cases I have treated responded to supportive care, NSAID's for fever, and fluid therapy, if necessary. In my experience, this condition is much milder than the bacterial colitis cases that we more commonly see.