We know that rotavirus—which causes severe diarrhea in foals—is a highly contagious virus that can spread rapidly through your foaling barn. But results of new genomic research from Asian scientists suggests that horses are also susceptible to rotavirus from both cows and pigs.

“Our study, based on whole genomic analysis, has provided the first conclusive evidence that bovine and porcine rotavirus can be transmitted to horses,” said Souvik Ghosh, BVSc, AH, MVSc, PhD, lecturer in the department of hygiene at Sapporo Medical University School of Medicine in Japan.

Rotavirus is made up of 11 gene segments that can “reassert,” meaning they can blend with other rotavirus strains to create a new, mixed strain, Ghosh said. For example, previous study results have shown that a rotavirus from cattle could mix with a rotavirus from a horse to create a new rotavirus strain that has nine bovine gene segments and two equine segments.

However, Ghosh’s study is the first to show that horses can be infected with rotavirus strains in which all 11 gene segments are bovinelike, meaning they are 100% bovine rotavirus strains. In other words, the disease can no longer be considered species-specific.

In a pioneering study, Ghosh and colleagues carried out whole genomic analysis of rotavirus strains found in horses. These included three “common” strains and one “unusual” strain, found in diarrheic foals in Japan. The common strains turned out to be genomically very similar to other common equine rotavirus strains throughout the world. The unusual one, however, had 11 out of 11 bovine gene segments.