Horse Health Alert: Equine Herpes Virus Strikes Horses in Upper Midwest States

Horses in Minnesota and Wisconsin are at risk for the contagious virus; two Minnesota horses were euthanized and additional horses have received positive diagnoses.

Lynn Hovda, Chief Commission Veterinarian for the Minnesota Racing Commission, describes what one racetrack in that state is doing to prevent EHV in this clip from local ABC news.

News alert from the Minnesota Board of Animal Health:

Equine practitioners in parts of eastern Minnesota and western Wisconsin have reported horses with acute neurologic signs.

Four of the affected horses have tested positive for equine herpesvirus-1 (EHV-1) infection (non-neuropathogenic strain). Two of the positive cases were horses on the same premises in Chisago County, Minnesota. One of these horses has made a full recovery; the other was euthanized.

One of the most recent cases was a horse in Dakota County, Minnesota. This horse has been euthanized. The other new case is a horse in Hennepin County, Minnesota; this horse is recovering. Diagnostic tests are pending on two additional horses.

Equine herpesvirus-1 is a highly contagious virus that causes respiratory disease, abortion, and intermittent outbreaks of neurologic disease in horses. 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 by submitting nasal swabs and whole blood in EDTA tubes to UC-Davis for real-time PCR analysis. Information about sample submission is on the UC Davis website.

The neuropathogenic strain of EHV-1 is a reportable disease in Minnesota. Test results that are confirmed to be the neuropathogenic strain of EHV-1 must be forwarded to the Minnesota Board of Animal Health.

The University of Minnesota Center for Animal Health and Food Safety recommends that horses with a fever and symptoms of contagious respiratory infection should be kept at home and not taken to shows, clinics or public trail rides. Horse owners should also be aware that transportation of horses to competitions, shows and clinics may increase the risk of exposure to infectious organisms. 

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.

(end of state health alert)

The Wisconsin State Veterinarian published a similar alert, which was shared with veterinarians in that state. 

Irongate Equine Clinic in Madison, Wisconsin shared the information in the state veterinarian’s announcement with horseowners on Facebook.

On Wednesday, Millhouse Veterinary Services in Stillwater, Minnesota released a statement on the practice’s Facebook page: “There seems to be an EHV-1 outbreak developing in the Twin Cities area with barrel horses being the focus at the moment. There have been a few that have tested positive and a few with tests pendingbut showing neurologic symptoms. 

“At this time we recommend no horse travel, especially to barrel racing events, to limit exposure until we have more information. We will keep you posted as we get more information.”

A followup message on Friday afternoon added: “We think it’s important to point out that the EHV-1 outbreak is not just a ‘barrel horse’ issue. Horses of many disciplines and breeds have been in and out of facilities where there may have been exposure. 

“These horses in turn have traveled home to other horses and some to boarding barns. This is why we are recommending no travel during the outbreak to protect your own horse/s and to stop further spread.”




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