A Lane County, Ore., horse has died from and four others from the same stable have tested positive for neurologic equine herpesvirus-1 (EHV-1), Oregon animal health officials announced late yesterday (March 10).

A statement from the Oregon Department of Agriculture indicates that all 10 horses residing on the affected property have been quarantined, and those showing signs of disease are being treated. There is no indication that the virus has spread to other horses beyond those being quarantined, the statement said.

“At this point in time, the investigation shows that this is an isolated incident confined to the animals now under quarantine,” said Oregon State Veterinarian Brad LeaMaster, DVM, PhD. “Equine veterinarians in the state are well aware of this virus and are trained to take the proper steps when a horse is showing symptoms.”

LeaMaster said the exposed horses have not been moved from the property in more than two months. The horse that died had originally been purchased from an owner in Benton County, Ore.; the previous owner has been contacted and reports no signs of illness in any of their horses.

“The Lane County stable owner and all horse owners have been very cooperative and supportive of the disease control actions taken” LeaMaster said. “A neurologic EHV-1 diagnosis certainly gets the attention of equine veterinarians and horse owners. We have had occurrences of the disease in Oregon in the past. I’ve noticed what seems to be a higher degree of awareness of the EHV-1 disease with horse owners than there was just a couple a years ago.”

LeaMaster praised quick work by local veterinarians and Oregon State University’s Veterinary Diagnostic Laboratory in detecting the virus quickly and taking steps to limit any spread.

[brightcove videoid="3027535698001" title="Health Alert: Equine Herpesvirus"]

EHV-1 is not transmissible to people. The virus is naturally occurring and widespread in the equine population. It 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. EHV-1 can cause respiratory disease, abortions in pregnant mares, neurologic disease, and, in severe cases, death.

The most common way for EHV-1 to spread is by direct horse-to-horse contact. The virus can also spread through contaminated equipment, clothing, and hands. Clinical signs include fever, incoordination, nasal discharge, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy, and the inability to rise (recumbency). While there is no cure, the clinical signs of the disease are sometimes treatable.

Concerned area horse owners are strongly advised to contact their veterinarian if they have questions and to develop an appropriate prevention plan, including vaccination. Vaccination must go hand-in-hand with the use of best management practices. Horse owners should practice basic everyday biosecurity to protect their horses from being exposed to this virus, as well as other highly contagious pathogens.

Veterinarians are asked to call the state veterinarian’s office with any suspected cases of EHV-1.