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  • Etalon Admin

EtalonDx EHV-1 Susceptibility Clinical Study

Etalon Diagnostics' team of equine geneticists has kept a close eye on the recent world-wide equine EHV-1 outbreak. Our research team is expanding a clinical study to verify the corresponding genetics of a horse's susceptibility to developing neurological symptoms after exposure and infection. Read on to learn more about the nature of this virus and how you can help our team by participating in the clinical study and supporting its efforts.

How will this research help me or my horse?

If the study is successful, then we be able to analyze your horse’s genetics and determine who is at highest risk for developing severe symptoms. By knowing which of our horses are at high risk, we can make better decisions around traveling, shows, exposure and vet care.

How can I participate in the study?

With a simple pulled hair sample & by telling your barn mates! Please spread the news that Team Etalon needs hair or blood samples from horses with a known exposure to the EHV-1 virus or confirmed veterinary diagnosis. More details below on how to participate. With your help, Team Etalon hopes to be able to provide a level of safety and prevention for you and your horse. Read below for more information on the difference between EHV and EHM.

What is equine herpesvirus (EHV)?

EHV stands for Equine Herpes Virus. Equine herpesviruses are DNA viruses that are found in horses all over the world, and almost all horses have been infected with the viruses and have no serious side effects. EHV-1 can cause four manifestations of disease in horses, including neurological form, respiratory disease, abortion and neonatal death. It is currently unknown what causes some infected horses to develop the serious neurological forms associated with EHV1 that may be fatal. Etalon's team of researchers is hoping to determine a genetic component to a horse’s susceptibility to developing neurological symptoms (EHM) after infection.

What is equine herpesvirus myeloencephalopathy (EHM)?

Equine Herpesvirus Myeloencephalopathy (EHM) is another name for the neurologic disease associated with equine herpesvirus (EHV) that represents one outcome of infection. This occurs to a subset of infected horses and its symptoms are painful and sometimes fatal. Neurologic signs result from inflammation of the blood vessels, blood clots, and death of neurologic tissue. Cases of EHM occur singly or can affect multiple infected horses.

What are some of the signs of EHV?

After infection, the incubation period is typically 4-6 days, but may be as short as 24 hours. EHV-1 typically causes a two-phase fever peaking on day 1 or 2 and again on day 6 or 7. With respiratory infections there is often nasal and ocular discharge, but not a lot of coughing. There may be some persistent enlargement of submandibular lymph nodes (lymph nodes under the jaw). With the neurologic form, there are typically minimal respiratory signs, fever (rectal temperature greater than 101.5 degrees F) being the only warning sign. Neurologic disease appears suddenly and is usually rapidly progressing, reaching its peak intensity within 24 to 48 hours from onset of initial neurologic signs. Horses may develop EHM even without any preceding fever and/or respiratory signs. Clinical signs of the neurologic disease may include:

  • Incoordination

  • Hind limb weakness

  • Loss of tail tone

  • Lethargy

  • Urine dribbling

  • Head tilt

  • Leaning against a fence or wall to maintain balance

  • Inability to rise

How does EHV spread?

EHV-1 is contagious and spread by direct horse-to-horse contact via the respiratory tract through nasal secretions. It is important to know that this virus can also be spread indirectly through contact with physical objects that are contaminated with the virus, including but not limited to: human contaminated hands or clothing, contaminated equipment and tack, contaminated trailers used for transporting horses, contaminated wipe rags or other grooming equipment, or contaminated feed and water buckets. The air around the horse that is shedding the virus can also be contaminated with infectious virus. Although it is known that the virus can be airborne, it is difficult to establish the distance the virus can spread in this manner under typical horse management and environmental conditions.

Learn more about Equine Herpesvirus from our friends at the AAEP here. Access disease alerts, outbreak information and resources through the Equine Disease Communication Center here.

Here's a link to the original study:


Team Etalon needs DNA samples from horses with a known exposure to the EHV-1 virus or confirmed veterinary diagnosis.

DEADLINE TO SUBMIT SAMPLES: June 1st, 2021 (samples MUST arrive at the lab by June 1st to participate)

Requirements for the study:

- Mail in a pulled hair sample from horse (please have your vet contact us to submit blood samples or nasal swabs)

- Include veterinary diagnosis and/or exposure report

- Create an account in to receive submission form

In order to submit your hair sample:

1) Log in to your Etalon account or create an account

2) Choose your horse, or "Add" your horse to your account and add Horse name

3) Select “Study_EHV1" from the Packages dropdown (scroll down to the bottom of the list). Please order ONLY this package in order for there to be no cost associated.

4) Place your order, and follow the directions for submitting hair sample. 

Please note, we do not send out a kit. After you place your order, you will have the opportunity to print out a pre-filled hair sample submission form

Samples that are included in the study will receive follow-up information for results and publications.

Mail hair samples to: 405 El Camino Real, #234 Menlo Park, CA 94025. For more information or if you have questions, give us a call at (650) 380-2995 or send us an email at

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