Horse Equine Herpesvirus: Welfare and Biosecurity

Equine herpesvirus (EHV) causes respiratory disease, abortion storms, and neurological disease in horses, with major welfare and biosecurity implications for equine facilities.

Key Facts

EHV-1 and EHV-4 are the most clinically significant strains, causing respiratory disease and abortion
EHV-1 can cause equine herpesvirus myeloencephalopathy (EHM), a neurological form that can be fatal
The virus is latent in most adult horses and can reactivate under stress
Outbreaks at equine events have resulted in widespread facility closures and significant economic losses
Vaccines against EHV reduce disease severity but do not fully prevent transmission

Welfare Considerations

EHV causes substantial welfare impacts across its clinical presentations. Respiratory EHV causes fever, nasal discharge, and depression lasting 1-2 weeks. Abortion due to EHV causes fetal death and distress for the mare. Neurological EHM causes progressive hindlimb weakness, bladder paralysis, and often inability to rise — a serious welfare emergency with high euthanasia rates. Outbreaks generate stress from isolation measures and facility closures. Early detection through biosecurity, monitoring, and isolation protocols is essential.

What You Can Do

Vaccinate horses against EHV with a programme recommended by a veterinarian
Implement biosecurity protocols when horses return from events or mix with new horses
Monitor for EHV signs including fever, nasal discharge, and sudden ataxia
Support research into more effective EHV vaccines and treatment protocols