What is Equine Herpesvirus? 

Equine herpesvirus (EHV) is a family of equine viruses named by numbers including EHV-1, 2, 3, 4 and 5 with EHV-1,3,4 posing the most risk for domestic horses. EHV is a common DNA virus that occurs in horse populations worldwide. The two most common species are EHV1 and EHV-4; both can cause abortion, respiratory disease and neurologic disease.

EHV-1 most often causes a respiratory disease which is usually mild and self-limiting, however, rarely EHV-1 and 4 can cause equine herpesvirus myeloencephalopathy (EHM) a neurologic disease affecting the spinal cord and can be fatal. EHV-3 causes coital exanthema a venereal disease which affect the external genitalia. Horses can be carriers of EHV with no clinical signs and can spread the disease to other horses. Testing and quarantining affected horses in isolation is the primary way to control the disease. Vaccines are available but do not completely prevent any form the disease.

Clinical Signs 

EHV-1: 

  • Fever
  • Nasal discharge
  • Lethargy/Depression 
  • Neonatal death
  • Late-term abortion
  • Neurologic disease 
     

EHV-4:

• Fever 
• Nasal discharge 
• Lethargy/Depression
 • Neonatal death
 • Late-term abortion
 • Neurologic disease

Diagnosis: EHV-1 and EHV-4 are diagnosed through PCR testing by nasal swab, buffy coat sample (centrifuged blood), virus isolation from blood, or a significant increase in antibody titer in serum samples collected 2-3 weeks apart.

Treatment: Supportive care and rest are the chief treatments. Non-steroidal anti-inflammatory medications, such as phenylbutazone (Bute) or flunixin meglumine (Banamine) are used to control fever, pain, and inflammation. In some cases, antivirals and heparin are used.

Prevention: Vaccinations are available for prevention of the respiratory and abortive form of EHV-1 and EHV-4; there is currently no vaccine labeled for the prevention of the neurologic form of EHV (EHM). The best method of protection is always to maintain current vaccinations on all horses on your property and to follow correct biosecurity protocol when bringing new horses onto your premises or when travelling with your horse. 

Biosecurity: EHV is spread via aerosol particles from nasal discharge or from contaminated surfaces including people, clothing, feed and water, implements, and stalls; isolation is critical to preventing spread of the virus. Proper biosecurity measures include extensive disinfection of surfaces and equipment that come in contact with affected horses

LATEST EQUINE HERPESVIRUS ALERTS

January 26, 2023
Information Only
January 25, 2023
Broward County, FL
Outbreak Update
January 23, 2023
Florida, United States
Confirmed Case(s) - Official Quarantine