Diarrhea is a leading cause of disease in foals, affecting about 6% per year. In foals 7 days old and younger, it causes about 25% of disease. But diarrhea itself has many causes. One of the more worrisome causes to veterinarians is equine rotavirus (ERV) infection, which causes illness in nearly 100% of infected foals, and has high mortality rates in neonates and untreated cases.

Christian Leutenegger, DrVetMed, PhD, FVH, worldwide head of molecular diagnostics at IDEXX Laboratories, in West Sacramento, California, and Ron Vin, DVM, Dipl. ACVIM, also of IDEXX and the Myhre Equine Clinic, in Rochester, New Hampshire, discussed ERV during a Sunrise Session at the 2016 American Association of Equine Practitioners (AAEP) Convention, held Dec. 3-7 in Orlando, Florida.

Rotavirus can be found across the world, but within the United States veterinarians see higher numbers of cases in areas with large breeding populations, such as California, Florida, Kentucky, New York, and Texas.

Foals contract rotavirus via the fecal-oral route, meaning they ingest the pathogen in infected horses’ manure. Foals younger than 6 months of age are susceptible to ERV, with most clinical cases involving foals 3 months old or younger. Veterinarians have detected ERV in isolated cases of adult horse diarrhea, but they have not yet determined its clinical significance to this demographic