Coronavirus has been identified in the feces of normal foals and those with intestinal disease. However, there have been recent outbreaks of diarrhea and colic in adult horses attributed to coronavirus. Clinical signs include anorexia, lethargy, and fever. Colic and changes in fecal consistency are seen in some cases. Occasionally, rapid progression leads to death (or euthanasia), but most cases resolve with supportive care.
Diagnosis is by detection of the organism in feces by real-time PCR, electron microscopy, and virus isolation. Leukopenia due to neutropenia and lymphopenia are the most common hematologic abnormalities.