Alert: Equine Herpes Virus (EHV-1) in Wisconsin

Three Horses Test Positive, One Euthanized

Three horses from an equine boarding and training facility in Dane County have tested positive for equine herpesvirus-1 (EHV-1), says Dr. Paul McGraw, Wisconsin’s State Veterinarian with the Department of Agriculture, Trade and Consumer Protection (DATCP). 

EHV-1 is a highly contagious virus that causes respiratory disease, abortion, and intermittent outbreaks of neurologic disease in horses. Humans cannot acquire EHV-1. 

One horse became ill in late August, showing neurologic signs, and was humanely euthanized.

The other two horses became ill over the Labor Day weekend and are being treated by a veterinarian.

All three horses were vaccinated in spring for rhinopneumonitis, which is caused by an equine herpesvirus. Currently licensed vaccines are not labeled for the prevention of the neurologic form of EHV-1. 

Symptoms that should alert horse owners to the possibility of neurologic EHV-1 infection include fever, weakness and incoordination, and urine dribbling or inability to urinate. 

Horses with these symptoms should be examined immediately by a veterinarian. Suspect horses should be isolated from healthy horses and tested for EHV-1.

“Horses with a fever and symptoms of contagious respiratory infection should be kept at home and not taken to shows, competitions, clinics or public trail rides,” McGraw says. Horse owners should also be aware that transportation of horses to competitions, shows and clinics may increase the risk of exposure to infectious organisms. 

Although humans can’t be infected by EHV-1, they can aid in spreading it to their horses. Therefore, owners of affected horses should wash and disinfect their hands and change their clothes before coming into contact with healthy horses to prevent the potential spread of these infectious organisms. 

The Wisconsin Department of Agriculture, Trade and Consumer Protection is providing information resources and situational updates on its website at and on Facebook at, and on Twitter at




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