Epizootiological and virological studies of foal diarrhea associated with serotype 3 rotavirus

Epizootiological and virological studies were conducted on foal diarrhea occurring in 3 foal-raising locations in a light horse farm from March to July, 1987. At the first location, although 27 (75%) of 36 foals had developed diarrhea, the isolation rate of rotavirus (RV) was low (5/14 feces, 36%). Many of the foals had the disease as early as 23 days after birth. At the second and third locations, 21 (27%) of 78 foals and 41 (76%) of 54 foals were affected with diarrhea. Isolation rates of RV were 90% (20/22 feces) and 100% (26/26 feces), respectively. The diseased cases were observed throughout the short period from June to early July and on foals aged from 63 to 65 days. These findings suggested the importance of RV as a causal agent of foal diarrhea at the latter location, RV and/or other agents at the former location. All the 3 strains of RV represented from each location were identified as serotype 3 by plaque reduction neutralization test against the antiserums of serotypes 1 to 6 of RV. However, the 3 strains showed low cross-reactivity with antiserum of the serotype 3 of the equine RV.