There are nine equine herpesviruses, five of which cause disease in horses. The two most important horse herpesviruses are EHV-1 (which causes abortion, neonatal death, respiratory disease and neurological disease) and EHV-4 (which mainly causes respiratory disease). Other equine herpesviruses include EHV-3 (equine coital exanthema) and the gammaherpesviruses EHV-2 and EHV-5. All of these herpesviruses can be detected by virus isolation in cell culture or by PCR tests. Antibody to these herpesviruses can be detected by ELISA (for EHV-1 and EHV-4) or by virus neutralisation tests for all equine herpesviruses.
Equine herpesvirus 1 (EHV-1) is endemic in all equine populations throughout the world including Australia. Adult horses are reservoirs for EHV-1, and latently infected mares are the most common source of reactivation and shedding of virus within the horse population.
Abortion due to EHV-1 typically occurs without any warning. The first, and in most cases the only, sign of EHV-1 infection is an aborted foetus.
If EHV-1 abortion is suspected:
Collect fresh tissues from the aborted foetus (thymus, lung, spleen and liver). Place tissues in a sterile container. These tissues will be tested using a PCR protocol unless otherwise stated. Fixed tissues including spleen, lung, kidney and liver may also be submitted for histopathology to detect characteristic lesions of herpesvirus infection.
If active EHV-1 infection is suspected but the foetus is not available (acute and convalescent serum samples of the dam):
Submit serum samples for antibody detection by ELISA
- Collect initial blood sample (plain tube) for serum and transport to the laboratory within 12 hours of collection. Sample to be held at Gribbles Veterinary Pathology before testing with convalescent sample.
- A second sample should be taken from the horse at between 2 weeks (no less) and four weeks (no longer) after the initial sample.
- All samples should be transported to Gribbles Veterinary Pathology within 12 hours of collection.
- After the second sample has been received by Gribbles Veterinary Pathology, both samples will be referred together for paired serological analysis by ELISA testing.
EHV 1-4 screening test for moving horses onto a new property:
Collect blood sample (plain tube) for serum and transport to the laboratory within 12 hours of collection. The serum will be referred for ELISA testing.
Fresh tissue (thymus, lung, spleen and liver)
Collect fresh tissues from aborted foetus.