Extension > Agriculture > Livestock > Horse > Horse health > Equine Herpesvirus 1 (EHV-1)
Equine Herpesvirus 1 (EHV-1)
What is EHV-1
- Contagious equine virus that can cause four clinical presentations: neurological disease, respiratory disease, neonatal death, and abortion
Clinical signs
- Fever commonly precedes other clinical signs
- Respiratory Disease
- Fever, coughing, nasal discharge
- Abortion
- Usually occurs in late pregnancy (8+ months, but as early as 4 months) with no warning signs
- Neurologic Disease – also known as Equine Herpesvirus Myeloencephalopathy (EHM)
- Hind–end weakness and incoordination
- Leaning against wall or fence to maintain balance
- Urine dribbling or inability to urinate
- Down and unable to stand
Incubation
- Highly variable, incubation period may be as short as 24 hours, but is typically 4-6 days
- When neurologic disease occurs, it is typically 8-12 days after fever begins
How is the virus spread?
- The most common way to spread EHV-1 is by direct horse–to–horse contact
- EHV-1 can also spread indirectly through contact with physical objects contaminated with virus
- Tack, grooming equipment, feed and water buckets, people’s hands or clothing
Treatment
- Supportive care, anti-inflammatory drugs
- Antiviral medications for horses with the neurologic form
- Sling support for horses with severe weakness and incoordination
- Antibiotics may be given if your veterinarian is concerned about secondary bacterial infection
- Isolate affected horses to prevent spread of infection
Prevention
- Vaccines are available to control the respiratory and abortion manifestations of EHV-1
- Current vaccines do not reliably prevent development of the neurological form
- Your veterinarian may recommend vaccination to help reduce spread of the virus
Does EHV-1 affect other animals?
- EHV-1 does not affect humans, dogs, cats, sheep, goats, cattle, pigs, or birds
- Alpacas and llamas are susceptible to EHV-1
Additional resources
- Equine Herpesvirus – American Association of Equine Practitioners
- Equine Herpesvirus (EHV) Myeloencephalopathy: A guide to understanding the neurologic form of the EHV infection (3.62 MB PDF) – United States Department of Agriculture
