The U.S. is experiencing an increase in Equine Herpesvirus Myeloencephalopathy (EHM) cases in recent days (California, Florida, Kentucky, Maryland, New Jersey, New York, Pennsylvania and Utah).
Additionally, Europe has also been reporting outbreaks of an aggressive strain of the disease with some concern that associated cases are represented in U.S. numbers due to spread from equine imports. As these cases are manifesting on the cusp of the early spring show season, please take time to review information about this disease, consult with your veterinarian for preventative measures, and enhance your biosecurity protocols at home as well as at equine events.
Equine herpesvirus (EHV) is a contagious virus that can cause four clinical presentations including: neurological disease, respiratory disease, neonatal death and abortion. Equine herpesvirus myeloencephalopathy (EHM) is the neurologic disease that develops as a result of EHV infection. The virus has been associated with neurologic cases in llamas and alpacas, but has no effect on people or other types of livestock.
The virus is usually spread in nasal secretions between horses that are in close contact with each other or that share water or feed pails. The virus does not typically survive very long in the environment or on people or equipment. It is killed readily by most disinfectants, ultraviolet light and by drying. Infected horses are generally treated with supportive care. Anti-inflammatory drugs and antiviral medications are often used for those that develop the neurologic form of the disease.
EHM positive horses and EHM exposed horses must be quarantined as outlined in the Board of Animal Health EHM control plan. Board staff members will then work with herd veterinarians and horse owners to carry out the testing and observation protocols defined in the control plan before the quarantines can be released. Additionally, the Board of Animal Health will post addresses on their website of farms with confirmed EHM positive cases as well as events where those horses attended while contagious, until the quarantine has expired.