REGULATORY SERVICES

Equine Herpes Virus-1

Equine rhinopneumonitis virus (EHV-1 or equine abortion virus) is a highly infectious disease that usually affects the respiratory system. Occasionally, the virus may also cause neurological disease. Transmission likely occurs by inhaling infected droplets or ingesting material contaminated by nasal discharges or aborted fetuses. Clinical symptoms may include a fever, difficulty urinating, depression, and stumbling or weakness in the hind limbs. Supportive therapy is often used to treat these cases. In severe cases, horses will be unable to stand; these cases have a very poor prognosis.

Equine Herpesvirus Myeloencephalopathy Outbreak Update
An outbreak of Equine Herpes Virus-1 (EHV-1) apparently originated at the National Cutting Horse Association (NCHA) Western National Championships, held April 29 through May 8 in Odgen, Utah. According to a USDA situation report, as of May 19, 2011, a total of 997 horses were reportedly exposed to EHV-1 (either at the NCHA event or through contact with horses exposed at the event); 21 cases of EHV-1 infection and 12 cases of Equine Herpes Virus Myeloencephalopathy (EHM) have been confirmed; and 7 horses died or were euthanized.

To limit the potential spread of EHV-1 and to alleviate horse owners' fears of exposure, a number of events in many states have been postponed or canceled and two veterinary teaching hospitals have closed to non-emergency equine and camelid cases.

The American Association of Equine Practitioners (AAEP) has developed resources about EHV-1, EHM and the current outbreak, including FAQs and resources for horse owners.

Important information about EHV-1:

• Equine herpesvirus myeloencephalopathy (EHM) is caused by equine herpesvirus-1 (EHV-1). The virus most commonly causes respiratory infection, and not all infected horses will develop EHM;
• EHV-1 is a normally occurring virus found in the equine population; this outbreak is not being caused by a new virus or a new strain of a virus;
• Signs of EHM in horses may include nasal discharge, incoordination, weakness of the rear limbs and hind end, lethargy, urine dribbling, and decreased tail tone;
• Llamas and alpacas can also be infected with EHV-1 and may develop neurologic disease;
• Currently, there is no equine vaccine that has a label claim for protection against EHM;
• There is no specific treatment that has been proven effective for EHM;
• If your horse has potentially been exposed to an infected horse (or through contact with people or equipment that have been in contact with an infected horse), or is showing signs that could indicate EHM, quarantine your horse and other potentially exposed horses and contact your veterinarian.

For more information, please refer to AVMA@Work blog post on this subject.

Current Information by Affected State
For a situation report on affected horses by state for May 26, 2001, click here.

Update for May 26, 2011:
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 75 confirmed EHV-1 or EHM cases have been reported in 9 states (AZ, CA, CO, ID, NM, NV, OR, UT, WA)
• Of the 75 confirmed EHV/EHM cases, 58 cases are horses that were at the Ogden, Utah event. 
• There are 11 horses associated with this incident that are dead or have been euthanized. 
• There are 15 newly identified premises with suspect or confirmed cases identified this reporting period.

May 24, 2011
44 horses now test positive in nine Western states.
The first case of EHV-1 was confirmed in Nevada.
Horse owners in California are advised to avoid non-essential transport.

Equine Herpes Virus (EHV-1) Situation Report - USDA
May 19, 2011

Summary Information on Current SituationA total of 33 confirmed EHV-1 or EHM cases have been reported in eight 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 event.
Seven horses associated with this incident are dead or have been euthanized.

Current Information by Affected State
For a situation report on affected horses by state for May 19, 2001, click here and scroll down to page two.

Horse owners can now access the EHV webinar that was recorded on 5/25. The EHV Webinar is the third one on the list. Click here for viewing instructions.

The Virginia Department of Agriculture and Consumer Services encourages horse owners to participate in a web seminar tonight on Equine Herpesvirus-1 (EHV-1).

At 8 p.m. Eastern time, May 24, 2011, a web presentation will provide horse owners with an update on the status of the EHV-1 outbreak and timely information on EHV-1 disease, testing, how to monitor your horse for disease, and how owners can prevent EHV-1 spread with optimal horse management, hygiene, and biosecurity measures. Following the presentation, panelists will answer questions on EHV-1 for another 30 minutes.  
Click here for more information.
Register now!
The seminar is presented by TheHorse and Intervet/Schering-Plough Animal Health.

May 20, 2011
Statement from the Virginia State Veterinarian on Equine Herpes Virus-1