Equine Herpesvirus

Horses and ponies can be infected by a number of different herpesviruses, the most important of which are equine herpesvirus type 1 and type 4 (EHV-1 and EHV-4). These two viruses share a high degree of genetic and antigenic similarity, however they differ significantly in their pathogenicity. EHV-1 can cause respiratory disease, abortion and neurological disease and is the most economically important herpesvirus to infect horses because of its adverse effects on the horse breeding industry. EHV-4 mainly causes respiratory disease, but has been associated with abortion on rare occasions. Genetic analyses have shown these viruses have been evolving within the horse for millions of years, despite being first isolated in the 1930s.

Currently, there are no commercially available vaccines that protect against the more serious forms of the disease. The Animal Health Trust has an ongoing EHV-1 research program, which is studying both the genetics of EHV-1 viruses and how EHV-1-infected blood cells interact with blood vessels, a mechanism responsible for the serious clinical signs in the horse. These studies will contribute to designing better vaccines for the protection of horses and ponies.

The Animal Health Trust is one of four OIE Reference Laboratories for equine rhinopneumonitis, which includes disease caused by EHV-1 and EHV-4. The research and diagnostic laboratories work closely together to ensure that the most up to date and sensitive tests are used for diagnosis, we also train scientists from other laboratories and can provide research materials. We offer advice on how to manage outbreaks and the most appropriate samples to take for testing purposes.

The Animal Health Trust Diagnostic Laboratory Services can provide virus clearance testing to be carried out on selected tissues following gross post mortem examination elsewhere or as part of a complete post mortem investigation carried out by us on site.