The relevance of equine herpesvirus 1 (EHV-1) infection in a German thoroughbred stud: vaccination, abortion and diagnostics

The aim of the present study was to clarify whether an EHV-I induced aborti on can be prognosticated by an increase of antibody titres, virus shedding and/or viraemia and whether the current abortion diagnostic is suitable. In this context the immune response post immunization and a possible reactiva tion were of great interest. For this purpose blood samples of 32 mares between the ages of 5-21 years w ere regularly investigated during a period of two years before and after va ccination and pregnancy. Neutralization tests, indirect immunofluorescence tests as well as PCR and virus isolation were used for EHV-I diagnostics. I t could be shown that the horses reacted individually to vaccination. In 14 cases a EHV-l-reactivation was suggested. An abortion prognosis was not po ssible even using serological, virological and molecular biological paramet ers. In addition, virus shedding and antibody titres were individual. An ac ute infection was detectable by a significant rise of antibodies and viraem ia as well as virus shedding in the secretions. For the abortion diagnostic s the antigen detection in combination with virus isolation and PCR from fe tal lungs gave reliable results. In addition, the virological and serosa lo gical investigation of the mare is recommendable. For prophylaxis we would advise a regular vaccination and strict hygiene.