Published Date: 2011-09-11 10:46:23
Subject: PRO/AH/EDR> Equine herpesvirus, equine - North America (12): (MI)
Archive Number: 20110911.2761
EQUINE HERPESVIRUS, EQUINE - NORTH AMERICA (12): (MICHIGAN)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 10 Sep 2011
Source: Mlive.com [edited]
Thanks to a conscientious horse owner here, health officials are
hopeful that a deadly equine disease has been stopped in its tracks
after its 1st victim.
Tests confirmed Wednesday [7 Sep 2011] that the 23-year-old mare Justa
Sailin, put down 1 Sep 2011, had the much-feared equine herpesvirus-1
myeloencephalopathy, EHV-1, the virus that spread across 6 western
states and killed 13 horses in May and June 2011.
That outbreak resulted in canceled shows, costly quarantines and
testing, and national worry among horse owners. It was linked back to
the spring week-long National Cutting Horse Association Western
National Championships in Ogden, Utah, where U.S. Department of
Agriculture figures show a total of 421 horses were potentially
In all, 1685 other horses were considered subsequently exposed when
horses from the show returned to their own states or mingled at other
shows. But when the horse in Richland got sick last week, even before
a diagnosis was confirmed, her owner, Betsy Rohr Hoyt, initiated
precautions just in case, and that, veterinarians said, makes all the
Show horses, including Hoyt's, are routinely vaccinated against the
garden variety equine herpes virus that can make them very sick with
respiratory illness. But there is no vaccination to protect against
the occasional virus mutation that attacks the animal's central
nervous system and leads to almost certain death, said James Connell
of Town and Country Veterinary Hospital in Allegan, who treated the
For now, the only protection is to isolate animals that have the
disease, keeping home all animals that might have had any contact with
a stricken horse and taking extraordinary measures to prevent any
germs from leaving the farm, he said.
In his case, that meant a shower, a change of clothes, and the
purchase of new shoes when the requisite bleaching ruined the pair he
had worn on calls to the farm last week to treat the animal.
In Hoyt's case, it meant forgoing an end-of-the-year show with a
seemingly healthy hunter-jumper from another farm, days before lab
tests came back showing that EHV-1 was responsible for her mare's
death. Hoyt went into voluntary quarantine mode, taking stringent
"I just finished bleaching everything yesterday," Hoyt said Friday [9
Sep 2011]. "I had to pull everything out of the barns, and everything
was power washed, bleached or Lysoled, or thrown away."
While she waited for lab results, she didn't travel to other farms to
work horses she had scheduled there.
"That's huge," because this is a virus that can be transported not
only from horse to horse but by hitch-hiking on handlers from one
horse to another, said Steven Halstead, state veterinarian with MDARD
[Michigan Department of Agriculture & Rural Development].
Halstead said MDARD workers were on Hoyt's Piper's Acre Farm today [10
Sep 2011], beginning to go over travel records and trace any prior
contacts between the horses there and other animals. Luckily, Hoyt did
not participate in the Richland Horse Trials show last month [August
2011], and it is unlikely there is any connection between that show
and Justa Sailin's death, Halstead said. At this point, veterinarians
are not sure how the horse contracted the illness.
The 8 animals still on the farm must remain fever-free for 21
consecutive days before the official Michigan Department of
Agriculture & Rural Development (MDARD) quarantine put on today [10
Sep 2011] is lifted. So far, they have shown no signs of illness, Hoyt
Halstead and Connell said they were not aware of any other cases,
either. They are hopeful this will be the end of it.
"Betsy Hoyt manned up and did something she didn't have to do. It was
a selfless act" that benefited every other horse owner across the
region, Connell said. "It's the right thing to do," Hoyt said. "I
wouldn't be able to forgive myself if I got someone else's horses
[Byline: Rosemary Parker]
[A sad loss for the owner, but her precautions are admirable. It is
hoped that all horse owners will educate themselves on this virus and
learn to recognize the early signs of this disease.
Equine herpesvirus (EHV-1) infection in horses can cause respiratory
and neurological disease, abortion in mares, and neonatal foal death.
The neurological form of the disease is known as equine herpes
myeloencephalopathy (EHM) and has the potential to cause high
morbidity and mortality.
EHV-1 is easily spread and typically has an incubation period between
2-10 days. Respiratory shedding of the virus generally occurs for 7-10
days but may persist longer in infected horses. For this reason, the
isolation period recommendation for confirmed positive EHM cases is 21
days. Clinical signs of EHM in horses may include nasal discharge,
incoordination, hindquarter weakness, recumbency, lethargy, urine
dribbling and diminished tail tone. The prognosis for EHM positive
horses depends on the severity of signs and the period of recumbency.
Employing supportive treatment with intravenous fluids,
anti-inflammatory drugs, anti-viral drugs and other supportive
measures may be beneficial, since there is no specific treatment for
EHM. Currently, no EHV-1 equine vaccine has a label claim for
protection against the neurological strain of the virus.
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