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Updates on current disease outbreaks are listed here as they occur and will include the date listed, disease name, location and current status. Specific premises will not be named but the general location by town, county and state will be listed. When locations, events or horses are at risk they will be listed. Updates will be posted as they are received.



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Flathead County, MT
Outbreak Identifier: 5492
Alert ID: 2888
February 01, 2023
Confirmed Case(s) - Official Quarantine

Montana Department of Livestock

Number Confirmed: 5; 
Clinical Signs: Neurologic signs; 
Comments: Following multiple confirmed cases of equine herpesvirus myeloencephalopathy (EHM) in Flathead County, the Montana Department of Livestock is recommending that horse owners and event coordinators in the Flathead Valley limit travel and cancel events that bring horses from multiple sources together through February 6th, 2023. The recommendation is based on involvement of horses on 3 premises that attended events at two or more event centers in the area. The date of the department's recommendation spans 14 days which is one full incubation period (time from exposure to the development of clinical signs) of EHV-1 beyond known travel history of involved horses. If additional cases of EHV-1 are detected, this date will be extended. To date, 5 cases of EHV-1/EHM (3 confirmed and 2 suspected) have been reported on 3 separate premises. Four of the confirmed and suspected cases have been euthanized due to the severity of disease. The fifth animal is exhibiting mild clinical signs and is under quarantine. Exposed horses from the affected premises are also subject to quarantine for 21 days beyond the last date of potential exposure. The department reports that several of the affected horses had no travel history, but herd mates, who remain without symptoms attended events where they were exposed and therefore, likely contributed to disease spread at their home locations and other equine events. Horse owners who have attended events in the Flathead Valley in recent weeks should monitor their animals for fever (temperature greater than 101.5° F) or development of any neurologic signs for two weeks after their last travel. For more information go to: https://news.mt.gov/Department-of-Livestock/Department-of-Livestock-Recommends-Cancellation-of-Equine-Events-in-Flathead-County and https://www.equinediseasecc.org/equine-herpesvirus