Andrew M. Cuomo, Governor | Richard A. Ball, Commissioner
Jessica Ziehm

May 20, 2011

State Alerts Horse Owners of Ehv-1 Outbreak in Western U.S.

No New York Horses Known to be Exposed to the Virus; State Vet Offers Guidance

New York State Agriculture Commissioner Darrel J. Aubertine today alerted horse owners of an outbreak of Equine Herpesvirus (EHV-1) that is traced to horses that attended the National Cutting Horse Associationís (NCHA) Western National Championships in Ogden, Utah April 30 through May 8, 2011.  At this time, there are no New York horses known to have been exposed to the virus at the Utah show. 

The Department is closely monitoring the situation in the western part of the U.S. and has been in close contact with federal animal health authorities and other states.  Approximately 29 states are believed to have horses that were exposed to EHV-1 at the show.

Equine Herpesvirus is commonly found in equine populations worldwide, and can cause respiratory disease, abortion and sometimes neurologic disease.  While EHV-1 is highly contagious among horses, it does not pose a threat to human health.

New York State Veterinarian Dr. David Smith advises horse owners concerned about EHV-1 to contact their veterinarian.  In general, exposed horses should be isolated and have their temperatures monitored twice daily for at least 21 days.  If an exposed horse develops a fever or other signs consistent with EHV-1 infection, diagnostic testing should be performed.  Testing healthy horses is generally not recommended.

As a basic biosecurity measure, all newly purchased horses or horses that return from events should be immediately isolated from other horses for at least three weeks. These horses should be monitored for signs of illness, which could include fever, cough, lack of appetite, nasal or ocular discharge, swelling around the throat or incoordination. It is recommended to take the temperature on these animals twice a day during the isolation period, and have separate equipment. If a fever is recorded, a veterinarian should be called immediately. 

Direct horse-to-horse contact is a common route of transmission of EHV-1, but it can be indirectly transmitted as well. This occurs when infectious materials, such as nasal secretions, are carried between infected and non-infected horses by people or objects such as buckets, grooming tools, tack, etc.

Fever is one of the most common clinical signs, as well as coughing and nasal discharge.  Abortions caused by EHV-1 generally occur after five months of gestation.  Neurologic signs of the virus are highly variable, but affected horses may appear weak and uncoordinated.  Severely affected horses may become unable to rise.  The neurologic form of the disease is sometimes referred to as Equine Herpes Myeloencephalopathy (EHM).  Any horse in New York that exhibits signs consistent with neurologic disease should always be considered as a potential rabies case and therefore, handled with caution. 

New York did have two confirmed cases of EHV-1 in March that was linked to an incident at Cornellís Equine Hospital in which an infected foal died and a gelding that was exposed and confirmed with the virus is now recovering.

For more information on EHV-1, visit the American Association of Equine Practitionersí website or check USDA APHISí brochure on the virus. 

2011 Press Releases