This is a very common viral agent and although can be isolated from most foals it does not always cause disease.

The role of the virus is not clear but it is thought that disease occurs when a large concentration of the virus infects the foals or when it is combined with other pathogens e.g. ascarids, salmonella, cryptosporidium.

It affects the young foal less than 1 month of age and initially presents itself as not suckling and depression. Temperature often is normal. Profuse diarrhoea may occur in the following 24-48 hours, which may persist for 2-3 weeks.

Treatment consists of electrolyte and nutritional support often given intravenously or by nasogastric intubation.

This can be very labour intensive and expensive.

Prevention is centred around good hygiene and reducing the population density of foals e.g. numbers in one barn. It is also essential to ensure that the mare has adequate antibody levels against rotavirus and that the foal has obtained these antibodies via the colostrum.

Vaccination
A vaccine containing an inactivated oil adjuvanted equine rotavirus H2 strain can be administered to pregnant mares. This vaccine is administered intramuscularly on three occasions during the 8th, 9th and 10th month of pregnancy.

This vaccine is recommended to increase the rotavirus antibody level in the mare's colostrum and is recommended in situations where there is a high foal population or where there is frequent movement of animals e.g. mares at public studs.

Whether there is a coincidence or not but we have found that since using the vaccine on pregnant mares general incidence of diarrhoea has reduced on public and private stud and so we would recommend the use of this vaccine.

J.D.Puzio BVetMed MRCVS