A Marion County horse has been hospitalized after testing positive for the neurologic form of equine herpesvirus-1 (EHV-1).
The horse, which has been treated at Oregon State University’s (OSU) College of Veterinary Medicine’s Large Animal Hospital, began showing acute neurologic signs on April 28 and was immediately referred to OSU. The positive EHV-1 diagnosis was made April 29. All horses at the index property in Marion County have been quarantined. The Oregon Department of Agriculture (ODA) reports there is no indication at this time that the virus has spread to other horses beyond those being quarantined.
Preliminary epidemiological investigations are underway. In all, there are 20 horses at the Marion County stable. The stable owner and all horse owners have been very cooperative and supportive of the disease control actions taken, the ODA said.
The investigation shows that horses from the affected property have attended recent events held at the Linn County Fairgrounds in Albany on April 16-19, and the Oregon Equestrian Center in Eugene on April 25-26. While the risk to these horses appears to be low at this time, concerned horse owners are advised to contact their veterinarian.
Herpesvirus is a common virus that can lie dormant for long periods of time and then reactivate during a period of stress, which can result in clinical disease. While not transmissible to people, EHV-1 is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (the neurologic form). In many horses,