So, no one has heard anything about this?
It has been in the news and to me is fairly significant as there isn't an effective protocol for treatment and there is a high 48% or so death rate with this disease. That is much higher than WNV. It also has been transmitted via clothing, etc., not just horse to horse contact.
Ashley, you may want to do a bit of research online. The EHV-1 vaccine does not according to current research protect for the neurological form.
This is from one of the articles listed below.
TREATMENT
Vaccines are available for the prevention of respiratory disease and abortions related to EHV-1; however, no vaccine is currently available to prevent the neurological form of EHV-1. Some research even suggests that vaccination may predispose horses to the neurological form of EHV-1.
However, the majority of the horses affected in the UK were not vaccinated. Hence, there is controversy as to whether the vaccine predisposes horses to the neurological form of the disease.
The best form of prevention is to keep your horses at home, thus limiting horse-to-horse contact. If this is not possible, limiting horse travel is advised. Also, any horse returning to a facility or moving to a new facility should be isolated.
An isolation period of 30 days is advised as the herpesvirus may be shed in various secretions (tears, respiratory secretions, and abortive fluids, etc.) for at least 14 days.
In addition, stress may cause a horse (as in people) that has recovered to again begin shedding herpesvirus.
No specific treatment is available for EHV-1. Supportive therapy (such as IV fluids, bladder catheterization, etc.) and nursing care (keep horses quiet, minimize stress, etc.) are extremely important to an animal’s survival.
Antiinflammatory agents should be used in an effort to minimize damage to the spinal cord.
In the Ohio outbreak, acyclovoir, a human drug used in the treatment of herpes infections, was used. The efficacy of treating horses with acyclovoir is promising.
In horses that survive, recovery can take several months. In those horses that don’t progress to recumbency, a complete recovery can be expected, while horses that become recumbent and survive may continue with some degree of neurological deficit.
Although the neurological form of EHV-1 is uncommon, it is periodically seen in the horse population. For additional information regarding EHV-1, contact a veterinarian familiar with the prevention and treatment of equine herpesvirus.
- - -
California Equine Herpesvirus Update by: Erin Ryder, News Editor
March 20 2007 Article # 9165
Five horses have been confirmed positive for equine herpesvirus-1 (EHV-1) in San Mateo County, Calif. Results are pending on one other horse. Three horses have been euthanatized, and three are undergoing acyclovir antiviral treatment.
Wayne Browning, DVM, of Bayhill Equine, has been monitoring the cases. He will be leading a public meeting on EHV-1 at the Mounted Patrol Grounds in Woodside at 7 p.m. on Wednesday, March 21st.
Browning said veterinarians are still investigating the source of the virus. They are considering latency (the virus' ability to remain dormant in a horse and become active when the horse is stressed) as well as the possibility of exposure to an asymptomatic horse that was shedding the virus.
Three farms are under voluntary quarantine. Browning said one of the facilities adjoins the index farm, and some of the horses at the third stable were exposed to a horse that later developed clinical signs.
- - -
Herpesvirus Shuts Down Virginia Horse Shows by: The Associated Press
March 02 2007 Article # 9060
An outbreak of an equine herpes virus has prompted Virginia's state veterinarian to shut down all horse shows and public horse sales. At least five horses have tested positive and several northern Virginia counties have been quarantined. Wednesday (Feb. 28), the Virginia Department of Agriculture and Consumer Services announced that all shows and auctions would be canceled until at least Monday because of the highly contagious and potentially fatal equine rhinopneumonitis virus.
While the start of the horse season is weeks away, some preseason shows were affected by the order.
"We were planning to go to a local show in Virginia Beach this weekend," said Fred White of the Gentle Touch Stables in Hampton, Va. "Hopefully they can keep this from spreading. That's got to be the most important factor right now."
Racetracks in Pennsylvania and West Virginia are also not accepting horses from Virginia.
The airborne virus poses no known health threat to humans. In horses, it affects the respiratory system and can occasionally cause neurological damage.
Stable owners supported the decision by state veterinarian Richard Wilkes to stop shows and auctions.
The Virginia Horse Show Association has recommended no shows until at least March 11.
- - -
This email is being sent to alert you to the fact that there is currently an
outbreak of the neurotropic form of Equine Herpes Virus
-1 (EHV-1) on the peninsula. Two date, four horses from two
Montara boarding facilities have been euthanized.
Below are messages from Dr. Wayne Browning of Bayhill Equine and Dr.
Russ Petersen of Peninsula Equine.
Please use caution as it appears that this virus can spread without
physical contact. Further, even though we all vaccinate twice a year
for EHV-1 and EHV-4, apparently that does not help with the
neurotropic form of this virus. It's all very confusing. More
information will be available soon regarding limiting the outbreak and
treating affected horses.
Recommendations at this point are:
. Restrict the movement of your horses to and from the affected area.
. Watch for fever and unsteady movement/gait or difficulty standing
. Careful handling to prevent contamination: washing hands, avoiding
shared water buckets, tie posts, etc.
** From:
Bayhill Equine
Dr. Wayne Browning
123 Belmont Avenue
Redwood City , CA 94061
(650) 851-2300 . BayhillEq@aol. <mailto: BayhillEq%40aol.com com
As most of you already know there has been a recent outbreak of the
neurotropic form of Equine Herpes Virus (EHV-1) in Montara. This was
the first confirmed case in San Mateo County . To date, Bayhill
Equine is the only veterinary practice that has seen, or treated any
horse involved in this outbreak.Therefore, as many questions have
arisen, I felt I should respond to a previous post to let people know
the current status and avoid any misinformation.
I originally saw a 4-year old filly on Monday morning, March11, that
was unable to stand and had a history of fever 5 days earlier.
Another horse in the same paddock was also showing signs of ataxia
(incoordination). Based on clinical signs, history, and multiple
horses affected, a tentative diagnosis of EHV-1 was made and the
horses referred to UC-Davis. By 5:15 that afternoon, a positive
diagnosis was confirmed by laboratory tests. I called at area
veterinarians on Tuesday morning, which is where they got their
information. Both horses were started on Valcyclovir, but were
euthanized yesterday after failing to respond to treatment.
Two other horses on this ranch were febrile and were thus tested. One
was positive and one was negative. Of of these horses had gone on a
ride with members of a neighboring ranch one day prior to breaking
with a fever. Additionally, a 29 year-old mare was euthanized on a
second neighboring ranch after being unable to stand. She and one
additional horse tested positive today, March 15th. Therefore, these
three ranches are currently on a voluntary quarantine based on
recommendations from out practice and those of UC-Davis.
No new horse had been introduced on the primary ranch for 6 weeks, and
the last horse to do so was from Pescadero. Dr. Magdesian at UC-Davis
felt that a fomite, such as clothing or shoes, could have been the
introduction method. He did not believe it was a spontaneous
mutation. Additionally, Drs. Madigan and Dr. Ferraro are planning a
site visit after obtain ranch owner approval both to study and to make
further recommendations to contain the outbreak.
I have attached a copy of the letter I wrote today, which is an
updated version of the one posted on the 12th. Also, we have
additional pages covering prevention, treatment, and management that
are available. You may contact our office for these or with any
addtional questions regarding the status of this outbreak.
PS.
1) Obviously contact your regular veterinarian for information
regarding treatment, prevention, etc. I simply said that we have
those papers already available which include links to appropriate web
sites for the latest information, etc.
2) Bayhill Equine is working with UC-Davis to contact the ranch owners
to obtain permission to visit the properties. We will be there as well
to ask questions of them, etc.
3) We are holding a community forum for all boarders on the coast so
we can update them with the latest information as well in hopes of
limiting this outbreak
** From:
Russ Peterson, DVM MS,
PENINSULA EQUINE MEDICAL CENTER
http://www.peneq. <
http://www.peneq.com/ com/
These cases have been confirmed and their vaccination status is still
under investigation. The State Veterinarians have been advised and
will be meeting with UCD staff and others consulting on the
implementation of more specific guidelines for handling quarantines,
etc as these are voluntary at this time.
Restriction of movement of horses between affected areas and
surrounding horse populations is critical to prevent spread; as
contagious horses may not be showing clinical signs of illness. Until
more specifics are available regarding the scope and source of this
EHV-1 hotspot, we recommend strict movement restrictions to-and-from
the affected area, vigilant monitoring of healthy horses for fever or
other signs, preventive immunization and measures specific to the
population at risk, and SPECIAL consideration to potential spread of
the virus via owners, handlers, service staff ( farriers, trainers,
etc) by utilizing recommended biohazard transmission prevention
measures.
An overview of these management measures, EHV-1 information from
previous outbreaks, and links to informative web sites can be obtained
on our website ( www.peneq.com). Feel free to contact our staff or
your individual DVMs for updates which we will strive to keep current
as developments and info becomes available.
- - -
Purdue research
FINAL DIAGNOSIS:
Ataxia with Equine Herpes Virus Type 1 Infection in a Horse
History: A Thorough-bred mare, reportedly 17.5 years old, was submitted dead for necropsy to the Purdue Animal Disease Diagnostic Laboratory. The history included marked asymmetric ataxia for approximately four months. The animal did not respond to treatment for equine protozoal myeloencephalitis (EPM) and was euthanized. The owner reported herpes virus infection earlier in the year.
Gross Findings: Scattered petechial hemorrhages were seen in sections of spinal cord at the level of T17-L3, predominantly in the ventral and ventrolateral funiculi. The surrounding parenchyma was occasionally soft, with gray discoloration. The brain was grossly normal.
Histopathologic Findings: The main lesions in the spinal cord consisted of wallerian-like degeneration accompanied by non-suppurative myelitis with vasculitis. The degenerative lesions were present in all the sections examined, accompanied by minimal inflammatory lesions, with the caudal thoracic and cranial lumbar segments being the most severely affected, accompanied by multifocal hemorrhage. Multifocal non-suppurative encephalitis was observed in all sections of brain examined except the frontal cerebral cortex.
Discussion: The inflammatory reaction in sections of spinal cord from this animal was centered on blood vessels, occasionally accompanied by hemorrhage. These lesions are highly suggestive of a primary vasculitis with secondary ischemic injury to the neuroparenchyma. Immunohistochemistry revealed a positive staining for equine herpes virus-1 (EHV-1) antigen in smooth muscle cells of spinal arterioles, arteries, and veins. PCR for West Nile virus on a sample of spinal cord was negative. These results, as well as the reported previous infection by this virus, are highly suggestive of EHV-1 infection.
Herpes virus infection is ubiquitous in horses, and most animals are infected by the first year of life. Neurologic disease is an uncommon sequela to EHV-1 infection in horses and is usually, but not invariably, associated with a recent history of fever, abortion, or respiratory disease in the affected animal or herdmates. Myeloencephalopathy due to EHV-1 is commonly an epizootic disease, but may affect single animals in a herd. Pregnant or lactating mares may be more susceptible, although stallions, geldings, and foals have also been affected with this disease.
Natural EHV-1 infection is acquired via inhalation or ingestion of virus that is shed primarily from the nasopharynx. The incubation period for signs of neurologic disease after experimental and natural infection with EHV-1 is 6-10 days. This form of EHV-1 infection can occur at any time of the year, but the highest incidence is in the late winter, spring, and early summer, perhaps reflecting the seasonal occurrence of abortigenic EHV-1 infections during the same months. Neurologic signs are of abrupt onset, and horses may be found recumbent as the first evidence of the disease. Clinical signs most often reflect spinal cord lesions; ataxia and paresis of the pelvic limbs are common, and passive dribbling of urine is a characteristic feature. Signs may be mild and transient as recovery or compensation occurs with minimal lesions. With severe lesions, recumbency occurs in 12-24 hours from the onset of neurological signs. Sometimes ascending paralysis is observed and animals may die in coma or convulsion or be euthanized because of secondary complications. Morbidity rates ranging from less than 1% to almost 90% of exposed individuals and mortality rates ranging from 0.5-43% of in-contact horses have been reported.
The pathogenesis involves viral endotheliotropism and associated vasculitis and thrombosis in the central nervous system with resultant ischemia and myelomalacia. Immune mechanisms have been implicated, but immunohistochemical demonstration of EHV-1 antigen in neurons of affected horses and association of myeloencephalopathy with certain EHV-1 strains indicate that primary viral neurotropism might also occur. EHV-1 has been reported to maintain a latent state in lymphoid tissues, leukocytes, and trigeminal ganglia. Reactivation of latent EHV-1 infection after stress situations has been reported as a possible source of infection.
The cerebrospinal fluid from affected animals is often xanthochromic with elevated protein but normal numbers of cells (i.e., virtually none). During the early stage of the infection, there is a cell-associated viremia, and virus may be isolated from the buffy coat in affected horses; however, failure to isolate EHV-1 does not rule out the diagnosis. A 4-fold increase in serum neutralizing antibody titer is considered diagnostic for EHV-1 infection, and a single high titer (greater than 1:256) also suggests recent natural infection. PCR in whole blood, nasopharyngeal swabs, lymphoid tissues, and trigeminal ganglia is another valuable technique in supporting a diagnosis of EHV-1 myeloencephalopathy, but decreased or absent viral shedding due to stage of infection, previous vaccination, or viral latency might affect the viral DNA detection. Postmortem examination, including spinal cord histopathology and immunohistochemistry, are recommended to confirm the diagnosis of EHV-1 myelo-encephalopathy.
No specific treatment of equine herpes myeloencephalopathy is currently available; thus, management of horses with this condition is directed toward supportive nursing, nutritional care, and reduction of central nervous system inflammation. Treatment with the antiviral agent acyclovir has been recommended. Further studies are required, however, to evaluate the thera-peutic efficacy of antiviral agents in the treatment of neurologic disease associated with EHV-1.
There is currently no known method to reliably prevent the neurologic form of EHV-1 infection. None of the EHV-1 or EHV-4 vaccines currently available carry a claim that they prevent EHV-1 myelo-encephalopathy, and the disease has been observed in horses vaccinated regularly at 3-4 month intervals with inactivated and modified live vaccines. Nevertheless, it is recommended to maintain appropriate vaccination procedures in an attempt to reduce the incidence of the other manifestations of EHV-1 infection and reduce the magnitude of challenge experienced by in-contact horses. This may indirectly help prevent EHV-1 myeloencephalopathy.
This case emphasizes that EHV-1 infection, although of rare occurrence, has to be considered as a possible cause for gait abnormalities affecting single or multiple horses on the premises, in addition to other viral myeloencephalitides, including West Nile virus, rabies virus, and togaviral encephalomyelitis, as well as equine protozoal myeloencephalitis, wobbler syndrome, cervical vertebral fracture, degenerative myelopathy, and a variety of plant and chemical intoxications.
-by Dr. Ingeborg Langohr, ADDL Graduate Student
- - -
Protocol for EHV-1 respiratory -
Pfizer recommendations
- - - - -
http://cvm.msu.edu/Extension/equine/up2004...rpesvirus-1.doc
2005 Update: Equine Herpesvirus-1 Outbreaks
The Equine Herpesvirus-1 virus can cause three different forms of disease that include: a respiratory disease (rhinopneumonitis, or sometimes called just rhino) which affects mostly young horses, abortions in pregnant mares, and neurologic disease (equine herpesvirus myeloencephalopathy).
Most commonly, this virus manifests itself as a respiratory disease in young horses. Abortion storms also occur in nonvaccinated pregnant mares.
The neurological form of EHV-1 is less common. However, in 2003, the respiratory outbreaks of EHV-1 often involved the neurological form with the outbreak at the University of Findlay in Ohio being the most devastating.
2003 OUTBREAKS
In 2003 a number of outbreaks of respiratory and neurologic illness occurred in the USA and the United Kingdom (UK).
In the Findlay, Ohio outbreak, 90 percent of the approximately 140 horses had respiratory symptoms with about one-third of the horses also having neurological symptoms. EHV-1 caused the demise of approximately 12 horses displaying neurological signs.
The source of the Ohio disease outbreak remains somewhat of a mystery. However, the disease was most likely brought to the Findlay campus with the arrival of new horses at the beginning of a new semester. The disease was confined to the equestrian facility.
All of the horses were vaccinated prior to their arrival on campus, which is a requirement of the facility.
In March, a least four facilities in the United Kingdom reported the occurrence of EHV-1 neurological disease.
Similar clinical signs were reported in the British cases, although fewer horses were neurologically affected at each facility.
2004 OUTBREAKS
Small outbreaks of neurological EHV-1 occurred across the United States in 2004, but no major outbreaks were reported for most of the year.
However, since December 2004, EHV-1 has created a major problem for the equine industry and the Standardbred horse seems to be the target.
In December 2004, two barns at Northville Downs Race Track, Northville, Michigan, were quarantined due to an outbreak of neurological EHV-1. Three affected standardbred race horses were euthanized.
After being closed for a period of time, the racetrack reopened in early March for live racing.
2005 Outbreaks
In early 2005, Standardbred race tracks in Pennsylvania and Nova Scotia (Canada) have been affected. In total, about a dozen horses have died or were euthanzied.
With each incidence, the racing facilities have acted responsibly by quarantining the stables while the outbreaks were diagnosed and the affected horses were treated.
In Michigan, the Michigan Department of Agriculture (MDA) has been involved in identification, monitoring, and quarantine of the affected horses.
CLINICAL SIGNS
Initially, horses may present with fevers up to 1050 F. Some horses will develop nasal discharge, depression, and loss of appetite.
Horses may also develop neurological signs, including toe-dragging, weakness, and incoordination of the hind end. The nerves of the head (cranial nerves) are often not affected. Other neurological signs that may occur include a weak, floppy tail, inability to defecate, and urinary incontinence.
Once innervation to the urinary bladder is affected, the horses cannot urinate freely and the bladder becomes greatly distended. After reaching the point of overfilling the bladder, they start to “dribble†or “squirt†urine. If these horses are not immediately treated by bladder catherization, permanent urinary incontinence may develop.
Some horses will progress to the point of recumbency. Once recumbent, a horse is extremely difficult to manage and is often euthanized due to treatment difficulties or for humane reasons.
The neurological form of EHV-1 must be differentiated from other diseases (such as rabies, EPM, EEE, WEE, VEE, and WNV). Equine herpesvirus affects only equids and does not pose a health risk to people or other animals.
TREATMENT
Vaccines are available for the prevention of respiratory disease and abortions related to EHV-1; however, no vaccine is currently available to prevent the neurological form of EHV-1. Some research even suggests that vaccination may predispose horses to the neurological form of EHV-1.
However, the majority of the horses affected in the UK were not vaccinated. Hence, there is controversy as to whether the vaccine predisposes horses to the neurological form of the disease.
The best form of prevention is to keep your horses at home, thus limiting horse-to-horse contact. If this is not possible, limiting horse travel is advised. Also, any horse returning to a facility or moving to a new facility should be isolated.
An isolation period of 30 days is advised as the herpesvirus may be shed in various secretions (tears, respiratory secretions, and abortive fluids, etc.) for at least 14 days.
In addition, stress may cause a horse (as in people) that has recovered to again begin shedding herpesvirus.
No specific treatment is available for EHV-1. Supportive therapy (such as IV fluids, bladder catheterization, etc.) and nursing care (keep horses quiet, minimize stress, etc.) are extremely important to an animal’s survival.
Antiinflammatory agents should be used in an effort to minimize damage to the spinal cord.
In the Ohio outbreak, acyclovoir, a human drug used in the treatment of herpes infections, was used. The efficacy of treating horses with acyclovoir is promising.
In horses that survive, recovery can take several months. In those horses that don’t progress to recumbency, a complete recovery can be expected, while horses that become recumbent and survive may continue with some degree of neurological deficit.
Although the neurological form of EHV-1 is uncommon, it is periodically seen in the horse population. For additional information regarding EHV-1, contact a veterinarian familiar with the prevention and treatment of equine herpesvirus.
Contact: Dr. Judy Marteniuk
Equine Extension Veterinarian
MSU College of Veterinary Medicine
(517) 353-9710
