Neurologic Equine Herpesvirus Outbreak in North Dakota

Horses on a property in Bottineau County, North Dakota, have died from neurologic herpesvirus.

Horses on a premises in Bottineau County, North Dakota, have died due to neurologic herpesvirus. iStock

On December 26, a presumptive diagnosis of neurologic herpesvirus was made for a deceases horse in Bottineau County, North Dakota. That property has 150 horses exposed. Two other horses were affected, but not tested for herpesvirus, and one horse that was clinically ill was laboratory confirmed positive for EHV-1.

The North Dakota State Veterinarian, Board of Animal Health, reported that as of January 10, the group of 150 horses is still under quarantine. Eight equine herpesvirus myeloencephalopathy (EHM or neurologic herpesvirus) cases have been identified (two laboratory confirmed and six presumptive). Of those, two horses died, three were euthanized, and three are recovering with mild neurologic signs of hindlimb ataxia and/or urine dribbling.

There have also been four abortions reported during this time period, including one from the EHM-positive horses that died. None of the mares or foals on the property are vaccinated. 

Information for this report was provided by the Equine Disease Communication Center (EDCC).

In a separate note from the EDCC listed on this North Dakota report, they stated, “Prior to the outbreak, on October 29, the North Dakota Board of Animal Health was notified by Brand Inspection of a shipment of bucking horses that had been moved interstate into North Dakota without health certificates, Coggin’s testing or brand certificates. The group of mares currently exhibiting neurologic signs are maintained on pasture 1/4 mile away from the location in Bottineau County where the illegally imported horses had been held.

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