RE: Need INfo on New Herpes Virus...
- Hi Craig,I can only find where there are 6 horses that have past since Nov 29 outbreak. Have you heard of more??? I hope the below article will help understand about the EHV outbreak. I found it very helpful.Kelly, Kasie & Koko in FL
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Seeing and understanding what you see are two different processes.
Anthony Gonzales PBM A Diary Of SoundnessThis is an update on the EHV1 situation in California provided by a polo
playing veterinarian. It is followed by an essay on prevention of the
problem and my view of the rational use of vaccines in general and
especially as used in the prevention of this particular disease. The essay
is long but it is an important and timely topic.
There has been a well publicized outbreak of the neurological form of EHV1
that has occurred in Wellington, Fla. over the past two weeks. This outbreak
has now spread to California. A cargo load of show horses shipped from New
Jersey to LAX on approximately 12/10/06. Included among the equine
passengers was a horse already deeply into the contagious form of the
disease that had vanned up from Wellington. After landing in LA, this animal
shipped to Del Mar. Within 48 hours of his arrival in Del Mar he began
showing a high fever (over 105) and signs of depression. Despite appropriate
treatment, he quickly showed the classic signs of weakness and ataxia
(drunkenness) involving primarily the rear legs. He became recumbent, was
unable to rise and was put down. This all happened within 72 hours of his
arrival in CA (source, Dr. Paul McClellan, private correspondence,
The other horses in the same load were unknowingly dispersed to various
points in CA. As of this writing, several are showing fevers and the barns
are under a voluntary quarantine. It remains to be seen whether these
measures will be sufficient to prevent further spread of the disease. Most
probably we will continue to see other small outbreaks. Please understand
that these outbreaks do not feel small if they occur in or near your barn.
The feelings that are generated among the unfortunate horse owning public in
proximity to an outbreak must be akin to what people worldwide felt in the
early part of the twentieth century as the Great Influenza Plague swept
world wide. The outbreak is not small if you stand any chance of being
involved. It is only through diligence that we will be able to control this
outbreak. The earliest signs of infection are fatigue, depression and fever.
Horses with this and many other diseases act like they have a deep, dull
head ache (to me, if a hors! e acts like he has a headache, he has a
headache). If you have a horse with these signs, especially if there has
been horse traffic in your barn within the previous 10 days, please call
your veterinarian. I will discuss the public's and the veterinarian's role
in controlling this outbreak toward the end of this essay.
It is interesting to note that the disease is currently not a reportable
disease in California. That means that health authorities are not required
to track the disease, to keep statistics on it or to disseminate information
to health workers. It also means that all quarantines in this state are
strictly voluntary in nature. Horse owners tend to be a responsible,
inquisitive sort and there would be intense peer pressure against any
individual knowingly breaking even a voluntary quarantine. There may also be
legal ramifications if a person willfully and knowingly breaks quarantine.
This would be similar, I think, to AIDS carriers being sued for spreading
the disease by continuing to engage in unprotected sex.
EHV1 is a herpes viral infection. Like other herpes viruses, it can lie
dormant within the body for weeks, months and even years. While dormant, it
escapes notice of the bodies own immune system until it can begin to
multiply rapidly enough to cause clinical signs. It is able to suddenly
multiply not by undergoing some mutation that allows it to escape
surveillance. Rather, it is via a breakdown in the body's immune
surveillance or response system. In essence, there is a "dip" in the ability
to mount an appropriate immune response. The most common cause of a
decreased immune response is that over worked word, stress. This can be in
the form of poor nutrition, pain, anti-inflammatory drugs used to decrease
pain, travel, changed social structures (think: break up with a boyfriend
and the cold sore that you sometimes get after that; of course, sometimes a
break up is a joyous occasion!) or concurrent disease states. Vaccinations
are a stress on the body sufficient to cause a tr! ansient but significant
dip in immunity.
The majority of EHV infections in horses are EHV1 or 4. EHV1 is much more
prevalent and more serious. There are three forms: respiratory, late term
abortions in pregnant mares or, rarely, the neurological form. EHV4 is
strictly respiratory infections. The neurological form is the most serious
and often progresses to recumbancy and death. Treatment is limited to
supportive help and some direct anti viral medication. Survivors are chronic
The neurological form of the disease tends to occur in sporadic but deadly
clusters. The first horses involved tend to be some population of horses
subject to typical show or race stress. The typical stresses felt by this
population include, but are not be limited to: intermittent travel, social
isolation (stall confinement), exposure to a changing population of equine
neighbors, exposure to other communicable diseases, performance in the face
of low or moderate grade musculo-skeletal injuries, performance enhancing
medications, a diet too rich in cereal grains but low in anti-oxidants,
short or little breaks from the same training routine and little to no time
spent outside, grazing green grass. There is often a history of a
vaccination within the preceding 60 days, sometimes even for
Rhinopneumonitis (EHV). Once started, infection can spread by direct
contact, aerosolized particles or mechanical vectors. The virus is not
especially long lived in the environment and is susc! eptible to almost all
properly applied disinfectants.
In 2004 there was an outbreak of the neurological form of EHV1 at Finley
University in Ohio. That outbreak claimed the lives of over 20 horses. This
was despite heroic 24 hour care provided by the two veterinarians on staff.
What was note worthy about that outbreak was that both the morbidity (attack
rate) and mortality (death rate) were higher in horses vaccinated for the
disease than among those never vaccinated (Dr. Stephen Reed, Ohio State
University, January, 2004, personal communication). I am aware of how
discouraging that statement reads to Vets and the public alike. If
vaccinated horses are at, the very least, not more immune to the
neurological form of EHV1, then what options do we have? We do have options
available to us. These include the proper use of vaccines and a larger view
of health. The answer to this puzzle lies in the way vaccines achieve their
Vaccines present to the body a modified form of the infectious agent that
the body can recognize as foreign and wage a brief and successful battle.
When exposed to the same infectious agent in the future (that is, exposed to
the disease), the response will be quicker and more efficient. The body wins
the battle without becoming sick at all or, perhaps, not as sick. Each and
every vaccination causes a transient dip in the body's level of immunity as
the body fights the battle and processes the information for the future use.
The more vaccines that are grouped together in one vaccine, the more
profound are the transient negative effect upon the bodies' immune status.
Grouping vaccines together also negatively impacts the bodies' ability to
respond to each individual vaccine. For the sake of convenience and economy,
most of our equine vaccines are grouped together in batches. For example,
the commonly used 4-way vaccine contains Eastern and Western
encephalomyelitis, Influenza !
(flu) and tetanus. We often add other vaccines at the same time such as
Rabies or Rhino. There is now on the market a 6-way vaccine which adds
Venezuelan encephalomyelitis and Rhino to the already over-loaded vaccine. I
would advise you to try to limit your use of these vaccines. Do not use the
6-way vaccine; the downside is greater than the potential benefit. Try at
the very least to avoid vaccination with more than one vaccine at a time. Do
not go to vaccine clinics where horses are vaccinated for many diseases at
the same time. If your veterinarian performs your vaccinations, see if you
can influence him to not group vaccines. Perhaps if you offer to van the
horse to his place of business or allow him to send a technician over to
perform the mechanical act of giving one vaccine at a time. More effort will
lead to better results and fewer complications.
The sense of urgency that we sometimes feel as regards vaccinations is
generally due to external perceptions about the need to vaccinate. This is
often due to the need to adhere to some new requirements such as travel to a
foreign country, a different state or to a new barn that has more stringent
vaccination requirements. The most dangerous sense of urgency comes as an
urge to vaccinate because of a fear of recent exposure to disease. The
desire to vaccinate in the face of a potential recent exposure is an
understandable one. After all, we are helping him to resist the disease,
The answer to that question, in the short term, is an emphatic no. It is the
short term that we are concerned about after potential exposure. We have
discussed how vaccination causes a short term dip in the immunity in
general. This dip in immunity is, logically but unfortunately, especially
pronounced for the disease we are vaccinating against! Thus, if your horse
has had potential exposure to EHV1 (also known as Equine Herpes or
Rhinopneumonitis) and is potentially incubating the virus, vaccinating him
will actually increase the odds that he develops clinical signs. In the case
of the neurological form of EHV1, this is a potentially fatal decision. For
most other diseases, the ramifications are not so dire. Sickness is usually
just an unfortunate event that horses and humans will generally recover
from. Nature is, after all, on our side.
The experience of vaccinating and aiding the appearance of clinical disease
was brought clear to me as when I worked as a farm veterinarian. I would
inevitably see an increase in the number of runny noses, coughs and fevers
following the herd administration of a round of flu/rhino vaccine given to
young foals. Unfortunately, at that time I could not put the facts together
correctly and, instead, reacted to the situation by stubbornly continuing to
vaccinate horses at a younger and younger age. Needless to say, this did not
solve the problem.
The correct response was probably to develop as hardy a group of foals as
possible in a large farm situation. This would include allowing them
opportunity for reasonable exercise (note: I did not say unlimited exercise
unless Darwinian survival is what you are after. Most owners will have a
very hard time with that explanation. I tried it once and will never go
there again), decrease relative and absolute over-crowding in all paddocks
and pastures, decrease dust and heat exposure and pay attention to correct
nutrition. Correct nutrition includes both the creep feed for the foals as
well as for the dam throughout her pregnancy. Also important is the benefit
of quarantine of new arrivals from young stock for 21 days. This will cut
down on preventable exposure. I know that vaccination is easier to institute
than this list. Institution of all of these measures on a farm at the same
time is seldom practical in my practice area. What remains true is that
vaccination, in-of-itself ! is not sufficiently effective and can, in fact,
be counter productive.
Does this mean we are not to vaccinate our livestock? Of course not, It does
mean that you, as the horse owning public and ultimate consumer, can easily
understand the more rational use of vaccines. Use the best quality vaccine
possible, use them sparingly but at appropriate times, group vaccines as
little as possible, separate their administration by 10 days, do not
vaccinate 21 days before or after vanning horses. Perhaps most importantly,
do not vaccinate in the face of possible exposure to a disease.
What then is the best response to possible exposure to a contagious disease?
The response would be the same whether the disease is influenza, Strangles
or, as in the current situation, EHV1. The rational approach is to bolster
the immune response.
Decrease stress as much as possible, increase the quality and quantity of
high quality nutritional support and begin immune stimulants as quickly as
possible. The immune stimulants that we use are generally of two types, the
oral supplements and the injectable medication designed for intra-venous
administration. These two forms of administration can and should be
combined. For oral support, we use Transfer Factor (Life Data Labs) and
Platinum Performance (Platinum Products). We follow label administration
directions. For IV use, Eq-stim and Zylexis (Pfizer) are the two choices.
Zylexis has been tested specifically against viruses prior to its recent
release on the open market. If there is a concern about exposure to EHV1,
use the Zylexis and the oral supplements as discussed. . The administration
schedule for both Eq-stim and Zylexis is similar. It is listed to give a
total of 3 injections, day 1, day 4 and day 7. At the least, separate their
administrations by 48 hours. A s! ingle shot helps, 2 shots are better than
1 and three better than 2. A situation may change dramatically in a short
time period and not necessitate the expense, time and potential
complications of IV shots. Stay informed and get the most current and
accurate information from your veterinarian.
In Ohio in 2003, Finley University had a large scale outbreak of the
neurological form of EHV1 in the show horse population. Despite heroic 24
hour care given by the 2 veterinarians on staff, over twenty animals died or
were euthanized. What is of interest in this case was that animals
vaccinated against EHV1/4 had both a higher morbidity (attack rate) and
mortality (death rate) as compared to the horses that no vaccinations at all
(Dr. Stephen Reed, The Ohio State University, private correspondence,
January 24, 2003).
There is yet hope to be gleaned from this grim fact. The few horses that
were vaccinated with a particular monovalent vaccine specific to EHV1, a
modified life vaccine, suffered no deaths. The numbers, however, were small.
Please understand, there are few miracles in life and there are no miracle
drugs. However, there is a difference in the immunity conferred upon your
horse depending on which vaccine you use. By far the preferred vaccine to
use in the present situation is called Rhinomune (Pfizer). It is a modified
life vaccine (easiest on the body), monovalent (no EHV4 or any other antigen
to dilute the immune response) and it is safe. This is the same vaccine that
was distributed by Norden in the 1970s and 1980s. It has been around for 35
years and has been proven to be safe. Do not use the Pneumobort K vaccine
made by Fort Dodge. This is a poor quality vaccine with poor ability to
stimulate immunity. Why else would brood mares have to be vaccinated with
numbing regularit! y at months 5, 7 and 9 every year of pregnancy? How long
would pregnant women remain quiescent if this were prescribed for them? Why
do our horses continue to have to be subjected to this vaccine? If we were
not so used to this situation we would raise our voices in disgust that this
vaccine is still around. More effective than Pneumobort K are the flu/Rhino
and EHV1/4 combination vaccines. These are better than nothing but horses
vaccinated with these vaccines have been shown to succumb to the disease and
In the simplest terms: Do not vaccinate your horse if your horse has
potentially been exposed to EHV1. Treat him like royalty for 21 days and
keep your ears and eyes open to what is happening in your local area. If he
shows no signs of disease at 21 days, go back to your old routine. Feel free
to vaccinate him at that point in time. The most effective vaccine to use
prior to exposure is Rhinomune (Pfizer). Repeat the vaccination in three
We must all be vigilant to stop the spread of this disease in California. If
you feel your horse is depressed, has a fever especially if there is nasal
discharge present, you can not assume, at this moment in time, that your
horse has a cold and will self-heal. Please call your veterinarian, ask him
to test the horse for Equine Herpes Virus exposure using blood (buffy coat
PCR) or nasal swabs (virus isolation). He may not want to come out (give the
guy a break, he deserves it). These are fairly simple diagnostic procedures
that can be performed by a veterinary technician. Give him verbal permission
to send a technician, and release him from liability concerns. The results
should be available soon and chances are overwhelming that you can stop
worrying. Your neighbors will appreciate your efforts.
Merry Christmas and good will to all, especially the hard working and
talented polo ponies of this world
Noel S. Muller, DVM
Los Caballos Equine Practice, Inc
Galt CA 95632
209 334 1660
- I have been told there is also an outbreak and quarantine in WY. Anyone
know of this?
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- I did find reports of an outbreak in Wyoming in 2001, but nothing
Cindy D., RVT
--- In firstname.lastname@example.org, Kim Foltz
> I have been told there is also an outbreak and quarantine in WY.
> know of this?
> thank you,
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> Virus Database (VPS): 0666-1, 12/31/2006
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Yes we have heard of more reported cases here in Fl.. From
Wellington,West Palm, to Ocala......
It seems each day we hear of more reports of more cases on the
different farms that are in quarenteen. Yesterday we heard
the "Tuxedo Farms" had a case....
so if this came from Germany, what are they doing to control it...
also Vets it this area are telling there clients that the "Rhino
Vac". will cover there horses...... this is different from all I
have heard to date but we know that is what is being told.....
so please help
We are just looking to clear up some things....