mares, neonatal foal death, and/or neurologic disease. The neurologic form of EHV-1 is called
Equine Herpes Virus Myeloencephalopathy (EHM). While EHV-1 and EHM are only officially
listed as reportable diseases in some states, private veterinary practitioners are encouraged to
notify their State Animal Health Officials of any suspected or confirmed cases, regardless of
current official state reporting requirements.
Cases of EHV-1 and EHM have been identified recently in horses that attended the National
Cutting Horse Association (NCHA) Western National Championship event in Ogden, Utah held
from April 29 to May 8, 2011. The NCHA has notified State Animal Health Officials of horses
from their states that were entered in the event and may have been exposed to the virus. State
Animal Health Officials have contacted the owners of potentially exposed horses. Standardized
recommendations were developed by state and federal officials and are being followed to isolate
exposed horses, monitor them for clinical signs of EHV-1, and work with private veterinary
practitioners to test and treat horses affected with the disease. Biosecurity procedures have been
recommended for premises with suspect and confirmed cases to mitigate further disease spread.
Read or download the report here:
Exposed Horses: Horses that attended the Ogden, Utah event from April 29 to May 8 and horses
that subsequently came into contact with horses that attended the Ogden, Utah event (secondarily
Exposed Premises: Premises with exposed horses.
Suspect EHV-1 case: A horse exposed to EHV-1 that develops fever (rectal temperature above
101.5 oF), but has no neurologic signs at this time.
Confirmed EHV-1 case: A suspect EHV-1 case with laboratory confirmation of EHV-1
infection, but has no neurologic signs at this time.
Suspect EHM case: A horse exposed to EHV-1 that develops neurologic signs. (Posterior
incoordination, weakness, recumbency with inability to rise, and/or bladder atony are most
commonly seen in EHM cases.)
Confirmed EHM case: A suspect EHM case with laboratory confirmation of EHV-1 infection.
Summary Information on Current Situation
• Owners of horses known to have been exposed in this incident have been contacted by
State Animal Health Officials.
• Suspect and confirmed cases are reported to be under voluntary or state quarantine.
• Known exposed horses are reported to be under either voluntary or state quarantine.
• A total of 33 confirmed EHV-1 or EHM cases have been reported in 8 states (CA, CO,
ID, NM, OR, TX, UT, WA)
• Of the 33 confirmed EHV/EHM cases, 32 cases are horses that were at the Ogden, Utah
• There are 7 horses associated with this incident that are dead or have been euthanized.