EHV-1 may lie dormant for long periods of time and then re-activate during a period of stress, which can result in clinical disease.
Two more Oregon horses have developed neurologic signs of the equine herpes virus (EHV-1). The total number of equines in the state with neurological EHV-1 is now at four, according to the Oregon Department of Agriculture.
Five exposed horses have developed fevers, but aren’t showing neurologic symptoms. Eight stables are currently under quarantine. Six are in Marion County and two are in Polk County. The index horse, from Marion County, tested positive for the neurological form of the virus in late April.
The infected or exposed horses attended several recent events, including an Oregon High School Equestrian Team (OHSET) meet at the Linn County Fairgrounds on April 16-19. The equines were at rodeo events at Branton Arena, in Jefferson, from April 19-20 as well as at the High Prarie Arena, in Eugene, from April 25-26. ODA continues to investigate the potential of any additional exposures.
State Veterinarian Dr. Brad LeaMaster says, “all horses that attended the OHSET Willamette district meet on April 16-18 should refrain from any further shows or gatherings for the next 28 days and impose a self quarantine. Owners of stable mates of these OHSET horses should consult with their veterinarian to assess risk of exposure.” Dr. LeaMaster continues, “high risk horses should also refrain from shows or gatherings.”
Symptoms may include fever, decreased coordination, 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. While there is no cure, the symptoms of the disease may be treatable.
The Oregon High School Equestrian Teams state championship meet has been postponed. It was originally scheduled for this Thursday through May 17th in Redmond. Organizers say they hope to reschedule the event for June.
For more information about the virus, contact your local veterinarian.