February 2016 Issue - page 1

Vol. 23 No. 2
Our 23rd Year
February 2016
LANC., PA 17604
(Continued on page 4)
Heartache in Bucks County as Equine Herpesvirus Erupts
By Suzanne Bush
In an unthinkable Christmas
week tragedy at Mile View Farm
in Doylestown, Bucks County,
PA, three horses were eutha-
nized after being diagnosed with
the neurologic form of Equine
Herpesvirus, also called Equine
Herpesvirus Myeloencephalop-
athy (EHM). Just before New
Year’s Eve, a fourth horse was
“They didn’t deserve this,”
Dr. Craig Shultz says of the
farm’s owners and those who
lost horses. “But they’ve handled
everything really well.” Shultz
is Director of Pennsylvania’s
Bureau of Animal Health and
Diagnostic Services and he
praised the farm’s owners for
their response to the outbreak.
“The folks at the facility have
been wonderful. They’ve done
everything they could possibly
do; they’ve cooperated 1,000 per
This disease is one of those
which trigger the “all hands on
deck” response from regional
and state veterinary author-
ities. The goal is to contain
outbreaks, track horses that
have been exposed to horses
that have developed full-blown
symptoms and monitor quar-
antines. “It’s a story that has
played out across the country
hundreds of times,” Shultz
explains. “This is by far not the
worst, but they’re all terrible.
It’s a nasty disease.”
He said that there are still
some horses at the farm that are
“clinical,” meaning they have
fevers or have tested positive
for the disease and they’re being
observed. “The last update I had
from our regional veterinari-
an was there has not been any
deterioration in the horses that
were febrile. We just have to wait
it out.”
The Carrier in Your Pasture
According to the United
States Department of Agriculture’s
Animal and Plant Health Inspec-
tion Service (APHIS), by the time
they are two years old, almost
every horse has been exposed
to—and thus carries—the Equine
Herpesvirus (EHV). The mystery
is why the virus reactivates with
such apparent randomness and
ruthlessness. Shultz says the virus
circulates throughout equine popu-
lations, and “recombines its DNA
like all viruses do.” He says they
don’t know which factors come to-
gether to create the “perfect storm”
that generated so much heartache
at Mile View Farm.
Equine herpesvirus can cause
spontaneous abortion in pregnant
mares, and other strains can
cause upper respiratory disease
in yearlings and weanlings.
“That’s part of the syndrome.
Why some horses simply develop
these other manifestations and go
merrily on their way and never
get neurological we don’t know,”
Shultz said.
Although there have been
nine variants of EHV identified
throughout the world, the variants
that are most troublesome are
EHV-1, EHV-3 and EHV-4. “We
know that the virology is very
complex,” Shultz explains. “Any
of them could progress to the
neurologic. Any of those viruses
can produce EHM.”
Besides its ability to morph
from a less lethal variant to the
deadly neurologic form of EHV,
the virus is very good at hiding
its identity. “It’s a very difficult
to diagnose disease because early
in the stages these horses will not
test positive,” Shultz says. “And
then later they’ll go on to demon-
strate virus on Polymerase Chain
Reaction (PCR) testing or in their
blood. It’s very unpredictable.
That’s why when we see it, we
lock everything down.” PCR is
the method used by laboratories
to reproduce sections of DNA or
RNA, from a virus like EHV, for
Virus Spreads by Contact
Shultz says that EHM can
spread quickly—even before any-
one realizes an individual horse
is sick. “It’s spread by contact,
horse to horse,” he says. And
people and objects can spread it,
too. “Tack, water buckets, feed,
humans handling infected hors-
es.” People working around an
infected horse can unconsciously
spread the virus through the most
mundane barn chores such as fill-
ing water buckets or feeding. “It’s
not an easily aerosolized virus,”
Shultz explains. “We certainly
see, when these outbreaks occur,
those horses close to ground zero
are at greatest risk.”
He says it’s critical to
contain the disease. “Of the two
horses that died on December
21, one of those horses had been
at a show at Hidden River, NJ
on December 12. New Jersey
veterinarians have monitored the
situation closely. They’ve reached
out to all the people at the show.”
He says no cases of EHM have
been reported in New Jersey,
and that the disease appears to
be contained now at Mile View
Farm. The farm is under manda-
tory quarantine, which will last
for at least 28 days from the last
suspected new infection.
An Emerging Disease
According to APHIS, “the
virus can be reactivated during
Barns, Arenas and Footing
Feature! Pages 8 - 21
Cold weather tips for horse owners
from New Bolton … pg. 23
Join Penn State’s parasite research
project … pg. 4
Readers weigh in on Newlin Twp.,
Morgan & racing coverage … pg. 22
…and much more!
Chances are good that all these horses are carrying the Equine Herpesvirus. The virus can remain
inactive and horses will show no sign of infection. Stress, such as strenuous exercise, long distance
transport or weaning can reactivate the virus, and it can on occasion recombine into the often fatal
neurologic form. The increased severity of recent outbreaks have led to the designation of EHM as
an emerging disease.
Photo credit: Suzanne Bush
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