Equine veterinarians at the University of Minnesota have diagnosed three cases of neurologic equine herpesvirus 1 (EHV-1) in horses from a single farm in the state’s Wright County.

Prompt recognition of the likelihood of EHV-1 infection ensured that two of these cases are now in isolation at the University’s Large Animal Hospital, which is a separate facility located a half-mile away from the Leatherdale Equine Center and Piper Performance Clinic.

The third case was euthanized on the farm.

Four remaining horses on the farm are being monitored closely at home.

Tests from one of the hospitalized horses yielded positive confirmation of EHV-1 infection on Wednesday, November 14 and tests from the second horse are pending. Since the farm of origin has been closed to on- and off-farm horse traffic for at least the past 6 months, there is a very little chance that additional horses have been exposed as part of this outbreak.

Stringent infection control protocols were implemented immediately at both the Leatherdale Equine Center and Large Animal Hospital. Isolation stalls are in use to protect other hospital patients and the equine community at large.

Biosecurity measures in use on campus include physical and airspace quarantine of the affected horses, closure of the Large Animal Hospital to all horses except those that may become affected as part of this outbreak, restriction of access to the Large Animal Hospital to essential personnel only, maintenance of separate veterinary and technical care teams at the Leatherdale Equine Center and Large Animal Hospital, and management of cases by board-certified specialists in Large Animal Internal Medicine and Infection Control.

The Piper Clinic in the Leatherdale Equine Center will remain open to serve the needs of our clients, and enhanced biosecurity protocols are in place to ensure the safety of horses admitted to that separate facility.

University of Minnesota reported this afternoon that the isolation unit includes a sling if either of the affected horses needs it, and that the isolation capabilities even include separate ventilation and air filtration for the sick horses.

The main large animal hospital, where the sick horses are housed in isolation, is not near the Leatherdale Equine Center, which is located in a separate part of the campus. Officials said that the presence of the two sick horses should not affect any horses at the Equine Center.

Equine herpesvirus-1 is a highly contagious virus that causes respiratory disease, abortion, and intermittent outbreaks of neurologic disease in horses.

There is no evidence that additional horses have been exposed in the Wright County outbreak, but symptoms that should alert horse owners to the possibility of neurologic EHV-1 infection include:

• fever,
• weakness and in-coordination,
• urine dribbling or inability to urinate.

Horses with these symptoms should be examined immediately by an equine veterinarian.

Horses with a fever and symptoms of contagious respiratory infection should be quarantined from other horses at home. They should not be taken to shows, clinics, or public trail rides. Owners of affected horses should wash and disinfect their hands and change their clothes before coming into contact with healthy horses to avoid the spread of viral or bacterial infections.

For additional information on EHV-1, please download the USDA Equine Herpes Brochure