Wednesday, November 23, 2016

All the Horses Say Neighhh: Equine Herpes virus

Equine Herpes virus (EHV-1) is a member of the viral family Herpesviridae, and causes equine abortion in an infected mare. There are nine strains of equine herpes viruses that are associated with a condition known as Equine herpesvirus myeloencephalopathy (EHM), which is a neurological disease associated with EHV infection.

EHV infection causes damage to blood vessels in the brain and spinal cord, and leads to neurological signs such as: fever, decreased coordination, urine dribbling, inability to rise, lethargy, loss of tail tone, and leaning against a wall to maintain balance. This condition is diagnosed via PCR and a positive test will indicate the presence of an EHV strain.

The LA equestrian center was right to quarantine the 300 horses suspected of contracting this virus, as the EHV-1 virus can lead to abortion, encephalitis, and perinatal infection–resulting in pneumonia or death–in up to 70% of a preciously unexposed herd. In this outbreak EHV was unfortunately the culprit, luckily the California Department of Food and Agriculture is monitoring the outbreak closely.  The difficulty with this virus has to do with its life cycle, as it can alternate between periods of latency and viral shedding–much like human herpes viruses. 
Image Credit: APHIS brochure
There is a vaccine to prevent infection, and while its efficacy is debated it is preferable to treatment options, which are mainly supportive in nature. Since this is a viral disease that affects horses, treatment options include dramatic measure such as euthanasia, thus avoiding infection is essential.

While researching this virus, I couldn’t help thinking how large the viral world is, and how much more there is to be discovered.  This virus has fairly obvious neurological signs, and is thus easy to spot, but how many more equine viruses are lurking that we know nothing about simply because the horses can’t communicate symptoms? Until horse telepathy technology becomes available, we’ll just have to develop PCR and other viral detection techniques.

-Cynthia Taylor



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