A 4-year-old warmblood mare in Baltimore County, Maryland, tested positive for equine herpesvirus-1 (EHV-1) on Sept. 22 after developing clinical signs on Sept. 20.
The Maryland Department of Agriculture is conducting an investigation into the case.
EDCC Health Watch, a program by Equine Network, utilizes information from the Equine Disease Communication Center (EDCC) to create and distribute verified equine disease reports. The EDCC is a nonprofit organization supported by industry donations to provide open access to infectious disease information.
EHV 101
Equine herpesvirus is highly contagious and can cause various ailments in horses, including rhinopneumonitis, abortion in broodmares, and Equine Herpes Myeloencephalopathy (EHM).
Signs of EHV-1 infection in horses may include fever, cough, decreased appetite, depression, nasal discharge, and in pregnant mares, abortion late in gestation. Neurologic signs of EHM can include ataxia, weakness or paralysis, urine retention, loss of tail tone, and recumbency.
The virus spreads through close contact, contaminated equipment, or contact with infected individuals. Routine biosecurity measures and vaccination can help reduce viral spread, but prevention through hygiene and disinfection practices is crucial.
EHV-1 vaccines may reduce viral shedding but do not protect against the neurologic form of the disease. Implementing strict biosecurity protocols is key to disease control and prevention.

