I started writing about EHV-1 outbreaks back in 2003, when there was an incident that killed 12 horses and sickened many others. It touched at least three facilities, devastating horse owners, handlers, and veterinarians alike. Scientists first called the pathogen an “atypical viral strain.” They later developed a test that allowed them to determine that strain differs from the one that usually causes respiratory disease in young horses. Since then, there has been ongoing work to further characterize viruses causing the most severe kind of EHV-1 infection, the neurologic form.
Be sure to have dedicated grooming equipment for each horse to minimize chances of spreading infection (this applies even in times when all the horses seem healthy). This includes the rag in your back pocket you just used to wipe a horse’s nose, or any sponges.
In the 14 years since, our industry has seen its share of EHV-1 incidents, each resulting in a flurry of industry response, quarantines, and eventually resolution. With each new incident comes further planning on how best to control the neurologic form of infection.
Sometimes in my media role I feel like a broken record with charges to adopt biosecurity practices and efforts to explain concepts such as how either variant, wild or neurologic, can cause neurologic signs and, thus, warrant precautionary actions.
But understanding these concepts remains vital. The virus is idiosyncratic; there isn’t a single recipe for response. Every EHV-1 outbreak is different in the way it unfolds. How quickly caretakers detect signs of illness and the way authorities handle the index case—the first confirmed in an outbreak—will dictate how the incident goes. There are other important points to remember:
The index case isn’t necessarily the horse that reactivated (the first one infected). It might simply be the one that was exposed to a shedder—that might have never shown signs—and got infected. So it might not be possible to prevent an index case; it all boils down to our reaction to it.
Promptly removing the index case from the general population and quarantining it well away, ideally on a separate premises, makes good scientific sense. It isn’t always possible.
Color-code everything using dedicated equipment for each horse group. Buy color-coded gear, or mark supplies with colored tape. This can include sets of coveralls. If you have a variety of nationalities represented in your barn, the colors can transcend language barriers.
Think about your habits. Sure, you have dedicated grooming kits, but what about that rag in your back pocket you just used to wipe a horse’s nose? Designate one rag or bath sponge to be used per horse.
Take notes on what worked and what didn’t, if you’re involved in outbreak resolution, and be willing to talk with epidemiologists about the incident. Your involvement helps researchers build a library of understanding so future outbreaks can be handled in the best way possible or, ideally, even prevented. You never know: You might help researchers make a discovery.
Plan now. Yes, a lot of time, planning, and preparation go into preventing an outbreak, but much more goes into resolving one. We’re all busy; don’t wait until an outbreak happens to you.
What equine biosecurity methods do you use around your farm or facility?
This Viewpoint first appeared in the March 2017 issue of The Horse: Your Guide To Equine Health Care. This edition includes articles on mare behavior, defending against disease, more first-aid basics (part 1 was in the January issue), feeding horses with endocrine disorders such as Cushing's and equine metabolic syndrome, and more. It also includes as a bonus, the 2016 AAEP Wrap-Up, 52 pages of understandable take-home messages from the equine veterinary convention that concluded in December. If you aren't already a subscriber, pick up an issue here.