Equine rotaviruses: A review of old and new

Summary Rotaviral infection is the most common cause of foal diarrhoea, leading to severe dehydration and electrolyte derangements, which, left untreated, can be rapidly fatal. Until 2021, equine rotaviruses of group A (ERVA) were considered to be the only rotaviruses affecting horses; however, equine rotavirus group B (ERVB) has recently been identified in association with neonatal foal diarrhoea outbreaks. ERVA has been observed globally in many countries with large equine industries. Equine rotaviruses (ERV) are extremely contagious. Foals as young as 12 hours of age can show clinical signs. These clinical signs include inappetence, dullness, colic and characteristic watery diarrhoea that can be orange‐yellow to reddish‐brown in colour. Nowadays diagnosis relies mainly on qPCR—a test limited by the fact that PCR is a directed test requiring a priori knowledge of a pathogen's genome. The mainstay of therapy for rotaviral diarrhoea is supportive care since treatment directly targeting the virus itself is not available. Prevention relies on proper biosecurity protocols and, in the case of ERVA, vaccination of mares. Currently, researchers at the University of Kentucky are working on developing a vaccine for ERVB.