Rise In Neurologic Form of EHV-1 Cause For Concern

by | 12.05.2019 | 7:34pm

A new review reports that equine herpesvirus-1 (EHV-1)—specifically the neurologic form of the disease–is still a large threat to the equine industry, potentially disrupting training and breeding schedules; restricting movement of horses; and potentially cancelling equine events such as shows and races.

There has been a marked increase in the number of reported neurologic cases of EHV-1 (also called equine herpesvirus myeloencephalopathy or EHM), though what causes the neurologic form of the disease is still on understood, reports HorseTalk.

Drs. Fatai Oladunni, David Horohov and Thomas Chamber report that EHV-1 primarily causes respiratory disease, but that it can spread to other organs, causing severe issues like neurologic disease and abortion in mares. The virus can become latent, but can reactivate at any time.

EHM is now classified as an emerging disease of the horse; outbreaks have occurred in Africa, Asia, Europe, North America and Oceana, all with a higher number of fatalities than in the past. These outbreaks occur mainly in areas where horses from different origins congregate, such as at horse shows, veterinary hospitals, racetracks and riding schools. Poor biosecurity measures, stressors to the horse and international travel are all thought to play a role in the rise of EHM cases.

Most horses are exposed to EHV-1 or EHV-4 early in life; the vast majority (between 80 and 90 percent) of horses are infected by the time they are 2 years old. Vaccines do not completely protect a horse from EHV-1, so prevention of disease outbreak is encouraged.

The virus was first recognized 80 years ago, but there is still no effective drug against EHV-1 infection; care is focused on easing symptoms and reducing the spread of the disease, which can cost up to several thousand dollars depending on the size of the farm. Additionally, even when a horse recovers from EHV-1, his or her productivity may be reduced.

The researchers note that there is no scientific explanation for the different manifestations of EHV-1. The neurologic form of EHV-1 tends to peak at two to three days after onset of clinical signs, and can vary between horses, with some being merely unsteady on their feet and others showing complete paralysis.

Horses that become recumbent have a higher chance for complications that may include colic, pneumonia or bladder rupture; down horses are generally euthanized.

Read the review here.

Read more at HorseTalk.

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