Friday the 13th: Equine Herpes Virus Reported in Two More States

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Break a mirror. Open an umbrella indoors. Watch a black cat cross your trail. And be prepared for the worst on Friday the 13th.

Today's horse health headlines could make you into a believer in the bad luck of Friday the 13th, as officials in two more states announced outbreaks of Equine Herpes Virus. 

State officials in Wisconsin and Florida are reporting that one horse in each state was euthanized in the past 24 hours, but it's worth checking the map and updating the list of states with current cases or quarantines that are ongoing.


The Department of Agriculture, Trade and Consumer Protection (DATCP) in Wisconsin reported today that a horse kept at a 50-horse stable in West Bend has tested positive for equine herpesvirus-1 (EHV-1). 

The horse began showing neurologic signs earlier this week and was humanely euthanized. Three other horses currently have a fever and are being monitored while being held in isolation from the other horses in the barn. The premises has been quarantined, which means that there is no movement of equine animals on or off the premises. DATCP will work with the stable owner and the veterinarian to determine when the quarantine will be released.

EHV-1 is a highly contagious virus that causes respiratory disease, reproductive failure, 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.

“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.

Information provided by Wisconsin DATCP


In Florida, an equine premises in Palm Beach County was placed under quarantine after a horse displayed neurologic signs and was confirmed positive for EHV-1 via PCR. The 18 other horses on the premises currently are clinically normal. The index case has been euthanized for humane reasons. Biosecurity measures and twice daily temperature monitoring are in place. All states with traces have been notified. The Florida Department of Agriculture and Consumer Services will continue to monitor the situation.

Information courtesy of Equine Disease Communication Center (EDCC) 

New York

A new quarantine was added earlier this week in Erie County, New York. On May 6th three aged mares, all displaying neurologic symptoms, were confirmed positive for Equine Herpes Virus-1. Neurologic symptoms along with a positive EHV-1 polymerase chain reaction test (PCR) meets the case definition for Equine Herpes Myeloencephalopathy (EHM). Both EHV-1 and EHM are reportable in New York. 

All three mares are from the same farm. One of the mares has been euthanized for humane reasons. The entire farm has been quarantined. Biosecurity measures and twice daily temperature monitoring are in place. 

Information courtesy of EDCC and New York state veterinarians.


Horse quarantines have been lifted at Fonner Park in Nebraska, which signaled an easing of heightened requirement for horses from Nebraska who were training to gain entry at Prairie Meadows in Iowa.

Information courtesy of State Veterinarian Dr. Dennis Hughes and Nebraska Department of Agriculture.


One one barn remains under quarantine at Pennsylvania's Parx racetrack in Bensalem after seven horses tested positive at that track, leading to shipping restrictions in and out of the track, and isolation of barns with infected horses. Four horses died.

(EDCC report)


There have been no new cases of Equine Herpes Virus-1 (EHV-1) reported in Maryland since April 19, when two horses stabled at the same farm in Howard County tested positive for the non-neuropathogenic strain of the virus. The farm was placed on 30-day quarantine when the first case was confirmed on April 18. There has been no movement of horses on or off the farm since that date. No other EHV-1 cases have been reported in Maryland.

(Maryland Department of Agriculture update)