A draft filly in Manitowoc County, Wisconsin, tested positive for respiratory equine herpesvirus (EHV) on Feb. 2. The yearling has shown intermittent low-grade fever and mild respiratory signs since being acquired by her owners four months ago. She is currently quarantined, and four other horses have been exposed.
EDCC Health Watch is a program by Equine Network that uses information from the Equine Disease Communication Center (EDCC) to share verified equine disease reports. The EDCC is a nonprofit organization supported by industry donations, providing open access to infectious disease information.
EHV 101
Herpesvirus is highly contagious among horses and can lead to various ailments, including rhinopneumonitis, abortion in broodmares, and EHM.
In many cases, fever is the first or only sign of EHV-1 infection in horses. Other common signs in young horses include cough, decreased appetite, depression, and nasal discharge. Pregnant mares may not show signs before aborting, which typically happens late in gestation but can occur earlier. Neurologic signs like ataxia, weakness, and paralysis develop in horses with EHM.
Herpesvirus spreads easily through close contact with infected horses, contaminated equipment, or people who have been in contact with infected horses. Biosecurity measures such as hygiene and disinfection are crucial in preventing disease spread.
While current EHV-1 vaccines may reduce viral shedding, they do not protect against the neurologic form of the disease. Implementing strict biosecurity practices is key to minimizing viral spread, with prevention being the best form of disease control.

