Equine Herpes Virus (EHV): Should I be concerned and how do I protect my horse?

nasal discharge

What is Equine Herpes Virus (EHV)?
Equine herpes virus (also known as rhinopneumonitis or rhino), is a contagious virus that most commonly causes respiratory disease. This virus can also cause abortions in pregnant mares and, rarely, neurologic disease (equine herpesvirus myeloencephalopathy or EHM). EHM is caused by a mutation in the EHV-1 strain of the disease.

Most horses will encounter EHV at some point in their lives. Most horses are exposed as foals and some may remain latent carriers of the disease. This means the virus hides in the affected horses’ lymph nodes or nerves, and these horses can shed the virus when they become stressed. This is a problem because when one horse is stressed (i.e., traveling, at a horse show or the racetrack) many other stressed horses with weakened immune systems are probably in the same vicinity. This is how many outbreaks start.

This winter, there was an outbreak of EHM at the HITS show in Florida. There also have been cases of this disease reported in Gloucester and Hunterdon counties in New Jersey this winter. Affected farms and the HITS showground were quarantined to try to prevent spread of the disease.

How is the virus spread?
The virus is spread directly through contact (affected horse touching healthy horse), indirectly (sharing of common water source, feed buckets, grooming supplies, etc), and can be airborne.

What are signs of EHV?
Fever is the most common sign of EHV. Also common are manifestations of respiratory disease – coughing, nasal discharge, quiet or depressed attitude, and decreased appetite. The reproductive form causes late-term abortions. Signs of EHM include fever (which usually precedes the neurologic disease), loss of coordination (horse may look “drunk”), hind limb weakness, loss of tail tone, loss of bladder control, lethargy, or recumbency.

How do I protect my horse?
Unfortunately, there is no vaccine that protects against EHM. However, vaccinated horses shed the virus less and may transmit the disease less. We recommend twice-a-year EHV vaccinations (this is the “flu/rhino” vaccine) for horses that leave the farm or live at a farm where other horses come and go. Horses that have been exposed to a horse or farm were the disease is present should be boostered and quarantined.

Limiting exposure is the best way of preventing this disease. This starts with common sense procedures such as preventing nose-to-nose contact with other horses, not sharing equipment or water sources, and washing hands or using hand sanitizers after contacting another horse. Ideally, all new or returning horses to a farm should be quarantined for three weeks (not have contact with other horses, use separate feed buckets, pitch forks, wheelbarrows, etc, and caretakers should wash hands, etc., before contacting other horses). Disinfecting any equipment and trailers that may have contacted an affected farm or horse is also recommended. For information on biosecurity, check out our website- http://www.coltsheadvet.com/Biosecurity.html

Fortunately, EHM is very rare. Unfortunately, this disease is likely here to stay. Vaccinating and limiting exposure to the disease is the best we can do to prevent disease. Monitoring for a fever, the first sign of disease, by taking a temperature twice a day, is important in horses that have potentially been exposed. If you have any questions, please do not hesitate to contact us.

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