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Animal Science and Forages > ASF Blog > Posts > Equine Herpes Virus (EHV1) Outbreak

By Cindy McCall, Ph.D., Extension Horse Specialist

The recent equine herpes virus (EHV1)) outbreak in horses that participated in the Bucksnort Trail Ride in Tennessee has many Alabama horse owners nervous. Some Alabama horses were exposed at the trail ride, and the Alabama State Veterinarian’s office has notified owners of those horses about the necessity for isolation and careful monitoring of their horses. At this time, there have been no reports of horses in Alabama having the disease.

Equine herpes virus is a common infection in horses but poses no threat to people. Most adult horses have been infected with EVH1 at some time in their lives and are carriers of an inactive form of the virus. Stressors such as long distance transport or strenuous exercise can allow the virus to reactivate so that the horse may become ill and capable of spreading the virus to other horses. The active form of the virus can cause abortion in pregnant mares, respiratory infection and neurological symptoms. The neurological form of the virus causes a condition known as Equine Herpes Myeloencephalopathy (EHM). While EHM is a relatively rare disease when you look at the whole horse population, it is the cause of concern for most pleasure-horse owners.
Signs of EHM in horses are fever preceding the neurological signs, then incoordination, urine dribbling, decreased tone in the tail (it can be lifted easily without the horse trying to clamp it down), hind limb weakness, lethargy, leaning against a stall wall or fence and being unable to stand. If your horse exhibits any of these disease signs, you should contact your veterinarian.
The virus is spread from horse to horse through direct contact or contact with aborted fetuses or fetal membranes, by indirect contact with tack, towels, buckets and people who have been in contact with an infected horse. There are some common-sense steps you can take to protect your horse. First, stay home to avoid exposing your horse to active EHV1. If you do go to a show or trail ride, keep your horse away from direct contact with other horses. Avoid common waterers, wash racks, tie lines and grazing areas. Work out of your trailer, if possible, rather than renting a stall. If you do need to rent a stall, clean the floors and walls thoroughly to loosen and remove organic matter and then disinfect it prior to letting your horse in it. A solution of one part bleach to 10 parts water is an effective disinfectant when organic matter has been removed first. Try to minimize your horse’s exposure to horses in neighboring stalls. Isolate your horse from the herd when you return home. If you are traveling to horse facilities, be sure that you do not carry the virus home on your clothes or hands. Always scrub up, change your clothes and change or disinfect your boots between barns. If you do have a sick horse,  isolate it from the herd and always care for that horse last to prevent spreading illness.
There are several vaccines for the respiratory and abortion forms of EHV1, but none are labeled for prevention of the neurological form of the disease. EHM has been observed in horses which have been routinely vaccinated against EHV1. Consult with your veterinarian about the use of EHV1 vaccines.
Places to find additional information about EHM include:



Darksyde Acres

7/22/2012 10:00 PM
We have several horses on our property, so this was an informative article for us to read.

<a href="">Darksyde Michigan</a>