Equine Herpesvirus (EHV-1) Outbreak

Horses April 15, 2013 Print Friendly and PDF
Image:EHV-feature-image.jpgFind out more about the recent Equine Herpesvirus (EHV-1) outbreak and access links to recent reports and resources.



2012 EHV-1 Suspected Cases & Information

EHV-1 Outbreak
  • On May 10th, the Tennessee Department of Agriculture released a statement saying that they had received reports of suspected cases of equine herpesvirus (EHV-1) infection in horses participating in the Bucksnort Trail ride held April 23-30 in Humphreys County, TN.

  • The event drew approximately 100 horses from multiple states and animal health officials have also been notified in those states.

  • As of May 29, 2012, the Tennessee Department of Agriculture has received a total of nine reports of suspected or confirmed cases of EHV-1 in Tennessee horses. The neurological form of EHV-1 has been confirmed in one case. Six of the suspected cases have been confirmed as showing clinical signs of the disease and are being isolated and monitored. In two cases, horses have been humanely euthanized.

  • Below are links to various reports and press releases regarding states reporting EHV-1 cases.



For the most up-to-date information on the EHV-1 outbreak, follow eXtension Horses on Facebook and Twitter.


2011 EHV-1 Outbreak Information

  • Horses participating at the National Cutting Horse Association’s (NCHA) Western Championships show in Ogden, Utah during the period April 30 through May 8, 2011 are believed to have had opportunity of exposure to EHV-1.
  • A statement from the National Cutting Horse Association regarding the reported cases of EHV-1 at the event can be found at http://nchacutting.com.
  • The American Horse Council, American Association of Equine Practitioners, and the United States Department of Agriculture's Animal and Plant Health Inspection Service:Veterinary Service are working together to monitor the situation.
  • Final situational report (PDF) on the EHV-1 outbreak issued June 23, 2011 by the USDA's Animal and Plant Health Inspection Service.


What is EHV-1?

  • Equine herpesvirus is one of the most common respiratory diseases affecting horses. There are at least four equine herpes viruses.
  • EHV1 and EHV4 are the two herpes viruses that commonly cause respiratory disease.
  • EVH1 can also cause neurologic disease.
  • EHV-1 is commonly found in horse populations worldwide and was previously referred to as the equine abortion virus. Although EHV-1 is well known for causing reproductive disease, it is also known to cause respiratory and neurological disease.
  • Transmission occurs when infected and uninfected horses come in either direct (nose to nose contact) or indirect (through buckets, clothing, blankets that are contaminated) contact with nasal discharges of infected horses. The virus can travel via aerosol (in the air) for short distances.
  • In horses infected with the neurologic strain of EHV-1, clinical signs may include: nasal discharge, incoordination, hind end weakness, recumbency, lethargy, urine dribbling and diminished tail tone.


Online Resources

Find EHV-1 updates, informational resources and information on individual states on The American Association of Equine Practitioners' (AAEP) EHM & EHV Resources webpage.
The United States Department of Agriculture's Animal & Plant Health Inspection Service has collected a number of resources on EHV-1 including informational brochures about the disease, as well as outbreak information from previous years.

Extension Resources and Publications on EHV-1

Informational publication written by Dr. Kerry A. Rood, Utah Extension Veterinarian and Dr. L. Earl Rogers, Utah State Veterinarian. Read more about the background, clinical signs, diagnosis and prevention of Neurologic Equine Herpes Virus (EHV-1).
Informational articles and resources about EHV, provided by the Colorado State University Extension.
Informational fact sheet written by Jenifer Nadeau, Associate Professor and Equine Extension Specialist at the University of Connecticut. This fact sheet touches on the different types of equine herpesvirus, clinical signs, routes of transmission and how to protect your horses from EHV.

Biosecurity Information/Resources for Horse Farms

Learn about evaluation methods and advice for prevention, protection, and proactive ways of minimizing disease risk in your horse facility by watching this recorded webcast, hosted by Dr. Betsy Greene, Professor of Animal Science and Extension Equine Specialist at the University of Vermont.
The United States Department of Agriculture has provided this brochure with general suggestions and guidelines regarding biosecurity on horse farms, including topics on transporting horses and using disinfectants.
The American Association of Equine Practitioners has organized this document with various biosecurity guidelines and recommendations for farms that house horses with EHV-1 or horses that have been exposed to the virus. Read about management of manure and bedding, as well as methods of disinfection horse equipment and facilities.