“I want to thank California’s horse owners and veterinarians for their prompt and thorough actions to isolate and monitor exposed animals and contain this outbreak of EHV-1,” said State Veterinarian Dr. Annette Whiteford. “We also owe the success of this project in part to the outstanding isolation biosecurity measures implemented by horse facility managers, show/event managers and other professionals who work with and care for horses.”

It is important that the California horse owners remain vigilant as there is always risk of disease when horses of unknown health status are commingled at one location. Consistent, basic biosecurity practices play an important role in reducing risk of exposure to diseases such as influenza, strangles, pigeon fever, or equine herpes virus.

By implementing the biosecurity measures below, you can minimize disease risk:

• Minimize horse nose-to-nose contact with horses of unknown disease status.
• Don’t share equipment including buckets, tack and grooming equipment.
• Avoid using communal water troughs.
• Fill water buckets directly from the faucet to eliminate potential hose contamination.
• Limit human contact between horses or wash hands or use hand sanitizer between horse contacts.
• Prior to returning home from an event, clean and disinfect all equipment, including trailer, clothing, tack grooming supplies.
• Isolate all new horses or horses returning home for a minimum of three weeks. Isolation means no direct  contact with other horses or humans and no indirect contact via shared equipment.
• Consult your veterinarian to establish appropriate vaccination for your horse(s).

Horse owners are strongly encouraged to consult their veterinarian regarding these steps and others to determine how best to reduce the risk of your horse acquiring an infectious disease.

REAPPEARANCE OF WEST NILE VIRUS IN CALIFORNIA POSES RISK TO HORSES
Horse owners urged to pursue vaccination

The return of West Nile virus to California this year is renewing calls for horse owners to make sure their animals are vaccinated. In 2010, nineteen horses in California were diagnosed with the disease. All of the horses were either unvaccinated or incompletely vaccinated.

“Outbreaks of West Nile virus are still a risk for horses,” said California State Veterinarian Dr. Annette Whiteford. “Horse owners should contact their veterinarians as soon as possible to ensure vaccination status is current. If people get the necessary shots for their horses now, the animals will have optimal protection against the disease.”

Signs of West Nile virus include stumbling, staggering, wobbling, weakness, muscle twitching and inability to stand. Horses contract the disease from carrier mosquitoes and are not contagious to other horses or people. Not every horse exposed to the virus will die, however, over the past seven (7) years affected horses have experienced a 40% mortality rate.

CDFA is cooperating with the California Department of Public Health to detect and respond to the disease in California. Horses provide an additional sentinel for disease detection. For more information, click on http://www.cdfa.ca.gov/ahfss/Animal_Health/WNV_Info.html

(Following this Fact Sheet are several links for up to date information about the EHV-1 virus outbreak in California and general facts about the disease.)

A recent disease outbreak of Equine Herpes Myeloencephalopathy (EHV-1) has been traced to horses who attended the National Cutting Horse Associations’ Western National Championships in Odgen, Utah on April 30 – May 8, 2011. California horses who participated in this event may have been exposed to this EHV-1 virus.

The California Department of Food and Agriculture encourages owners of horses who participated in the Odgen, Utah event to isolate and monitor their horses for clinical signs of disease. A rectal temperature in excess of 102F commonly precedes other clinical signs. Therefore, we are urging owners to take temperatures on each individual horse(s) twice a day. If a temperature above 102F is detected contact your private practitioner immediately. Laboratory submission of nasal swabs and blood samples collected from the exposed horse can be utilized for virus detection and isolation.

The EHV-1 organism spreads quickly from horse to horse and the neurologic form of the virus can reach high morbidity (illness) and mortality (death) rates. The incubation period of EHV-1 is typically 2-10 days. In horses infected with the neurologic strain of EHV-1, clinical signs may include: fever, nasal discharge, incoordination, hind end weakness, recumbency, lethargy, urine dribbling and diminished tail tone. Prognosis depends on severity of signs and the period of recumbency. There is no specific treatment for EHV-1. Treatment may include intravenous fluids, anti-inflammatory drugs and other appropriate supportive treatment.

Currently, there is no equine vaccine that has a label claim for protection against the neurological strain of the virus.

The strain of EHV-1 causing neurological symptoms is a mutation of the EHV-1 virus most often associated with abortion in pregnant mares. There is NO vaccine for this strain. The commonly used 5-way or Flu/Rhino vaccine has EHV-1 antigens (the sensors that alert the body to produce antibodies to a specific disease) in the vaccine but the “load” of antigens is too low for protection in horses challenged by the virus. However, the Pneumobort-K vaccine and Rhinomune vaccine have a high antigen “load” against EHV-1, but still does not protect against the mutated strain of EHV-1. There is some thought that giving the Pneumobort-K vaccine or Rhinomune vaccine with a high “load” of EHV-1 antigen may be of benefit, but this is purely antidotal, and there is no research to support this protocol. Information suggest that both vaccines create similar immune response to EHV-1, however neither vaccine create direct protection to the mutated strain of EHV-1.

The disease is a virus and requires direct contact from horse to horse, or perhaps more commonly owners are contaminating their hands, and then contaminating others horses. Also, the virus can be airborne and transmitted as an aerosol to other horses. Common sense regarding direct contact with other horses should be used.

Horse-to-horse contact, aerosol transmission, and contaminated hands, equipment, tack, and feed all play a role in disease spread. However, horses with severe clinical signs of neurological EHV-1 illness are thought to have large viral loads in their blood and nasal secretions and therefore, present the greatest danger for spreading the disease. Immediate separation and isolation of identified suspect cases and implementation of appropriate management measures (contact your veterinarian for proper management, if you suspect you have a neurological EHV-1 horse) are key elements for disease control.

CONCLUSION: Monitor your horses for illness and/or neurological symptoms. Avoid contact with horses that you may suspect have had contact with the disease, and wash your hands between horses that you are not familiar with. Common sense and contacting your veterinarian if you have symptoms or concerns is the best approach. We encourage you to contact your veterinarian with specific questions.

California Department of Food and Agriculture Daily Update

UCDavis Center for Equine Health White Paper on EHM

EHM Owner Update

EHV-1/EHM FAQ’s

USDA Resources

USDA Equine Herpes Myeloencephalopathy Brochure

American Association of Equine Practitioners Fact Sheet

TheHorse.com Equine Herpesvirus-1 Myeloencephalitis (EHV-1/EHM) Resources

CDFA Equine Herpes Myeloencephalopathy Fact Sheet

USDA Biosecurity Brochure

Link to United States Veterinarian’s Directory

National Cutting Horse Association Website

Basic BioSecurity Brochure

These biosecurity guidelines have been developed by CDFA veterinarians and the faculty at the School of Veterinary Medicine, University of California, Davis, CA, to minimize the risk of transmission of infectious diseases at public equestrian events.
Based on what is known today, June 8, 2011, regarding the current neuropathogenic EHV-1 outbreak, we are suggesting that managers of horse shows or events occurring in California during the month of June 2011 incorporate the following biosecurity measures to minimize the risk for all participants:

1. Non- exposed horses: Event managers should create a short document for participants to sign upon arrival at the show grounds to confirm that their horses, mules, and burros attending the show/event have not been exposed to a clinical case of the neuropathogenic strain of EHV-1 and have not been on premises with a confirmed positive case within the prior 28 days.
* Clinical case is defined as a horse testing positive on a laboratory test for the neuropathogenic strain of EHV-1 and having exhibited compatible clinical signs for EHV-1 which may include fever, abnormal nasal discharge and/or neurologic signs.

2. For exposed horses: Event managers should create a short document for participants to sign upon arrival at the show grounds to confirm that their horses, mules, and burros attending the show/event have not demonstrated clinical signs compatible with EHV-1 for the preceding 28 days and no other horses on the premises where they reside have shown clinical signs (fever, abnormal nasal discharge and/or neurologic signs) for the preceding 28 days. Additionally, it is recommended that the owner/trainer of an exposed horse showing residual neurological deficits provide evidence of two negative tests for the neuropathogenic strain of EHV-1 within the prior 14 days.
* Exposed horse is defined as a horse which has resided on a premises with a confirmed positive EHV-1 horse or on a property which has had horses that have displayed clinical signs compatible with EHV-1 in the prior 28 days.

3. Establish a “No Fever” policy for horses attending the event. Give the participants prior notice of the new “No Fever” policy before they arrive at the show grounds. Provide instructions for obtaining the horse’s temperature and an index card on which to record temperature readings for each horse.
* All horses will have temperatures taken twice daily and results will be posted on front of the stall/pen for inspection.
* Any horse will be subject to random temperature check by the show veterinarian or designated member of the veterinary staff during the event.
* Any horse with a fever of 102°F or greater will be removed from the event and premises immediately (i.e. within 2 hours of detection of fever).
* If the owner cannot move the horse off the premises, a professional horse hauler contracted by the
event will remove the horse to a designated isolation area at the owner’s expense.

4. It is understood that some (most) horses with a fever will not have EHV-1; however, in the interest of conducting a safe event under the current circumstances, we recommend event managers use the non-fever policy. Participants who choose not to comply with these safety measures should be advised to not attend the event.

Click here to view certificate.