Equine coronavirus' main signs are subtle and nonspecific—anorexia, lethargy, and fever. And while it doesn’t consistently cause gastrointestinal signs such as colic or diarrhea, researchers have learned that affected horses’ feces are the most reliable sample to test. | Photo: iStock

Equine coronavirus is a relatively recently recognized infectious disease of adult horses. Its clinical signs of fever, lethargy, anorexia, colic, and diarrhea, however, can point to other diseases. This presents a diagnostic challenge for treating veterinarians. So what samples should a practitioner collect on a sick horse to confirm an equine coronavirus infection?

Nicola Pusterla, DVM, PhD, Dipl. ACVIM, professor of medicine and epidemiology at the University of California, Davis, School of Veterinary Medicine, attempted to answer this question during the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

“Equine coronavirus makes liars out of horses,” he said, “particularly horses with fever, but no respiratory signs (nasal discharge, coughing) and no gastrointestinal signs (diarrhea, colic). What sample do you collect? It has you scratching your head