EHV-1 Consensus Statement
http://onlinelibrary.wiley.com/doi/10.1111/j.1939-1676.2009.0304.x/pdf
http://www.aphis.usda.gov/vs/nahss/equine/ehv/
http://www.aaep.org/EHV_resourcesowner.htm
South Dakota Animal Industry Board
411 South Fort Street
Pierre, SD 57501-4503
Phone: 605-773-3321
Fax: 605-773-5459
FOR RELEASE – Equine Herpesvirus Contact: Dustin Oedekoven, DVM, State Veterinarian May 18, 2011
PIERRE, S.D. – Equine Herpesvirus (EHV-1) has been traced to horses that attended the National Cutting Horse Association’s (NCHA) Western National Championships in Ogden, Utah, on April 30 - May 8, 2011. Affected horses have been identified in some western states, including Colorado, Idaho, and California. Other states are investigating potential cases or tracing and monitoring horses that attended the event and returned home.
South Dakota State Veterinarian Dr. Dustin Oedekoven says South Dakota horses that attended the show in Utah are not showing symptoms of the disease.
“The owners have been contacted and advised to isolate exposed horses for three weeks, follow good biosecurity practices and watch for possible clinical signs”, Oedekoven said.
Equine Herpes Virus is a common virus in equine populations worldwide. There are several strains of the virus, with EHV-1 and EHV-4 being most often involved in clinical disease. EHV-1 can cause respiratory disease (also known as “rhinopneumonitis”), abortion and neurologic disease. The neurologic disease is sometimes referred to as Equine Herpes Myeloencephalopathy (EHM.) Although EHV-1 is highly contagious among horses, it does not pose a threat to human health.
EHV is transmitted primarily by aerosol when infectious droplets are inhaled. The source of infectious droplets is most often respiratory secretions. Direct horse-to-horse contact is a common transmission route for the virus, but indirect transmission is also possible. That occurs when infectious materials (nasal secretions, fluids from abortions, etc.) are carried between infected and non-infected horses by people or fomites (inanimate objects, such as buckets, etc).
Fever is one of the most common clinical signs and often precedes the development of other signs. Respiratory signs include coughing and nasal discharge. Horses with neurologic symptoms may appear weak and uncoordinated. Urine dribbling and loss of tail tone may also be seen. Severely affected horses may be unable to rise. None of those signs are specific to EHV, and diagnostic testing is required to confirm EHV infection. Many horses exposed to EHV never develop clinical signs.
Equine herpesviruses are common, and EHM has been reported in South Dakota in past years. If you suspect your horse has been exposed to EHV, contact a veterinarian. In general, exposed horses should be isolated and have their temperatures monitored twice daily for 10 days. If an exposed horse develops a fever or other signs consistent with EHV infection, diagnostic testing should be done.
“If you travel with your horse, good biosecurity practices can reduce the risk of disease transmission” said Dr. Oedekoven. “Cleaning and disinfection of feed and water buckets, stalls, and trailers is important in preventing the spread of disease. Horse owners can minimize spread of EHV by implementing a 21-day isolation policy when adding new horses or returning horses to established herds.”
Vaccines effective in preventing respiratory and reproductive EHV are widely available and should be administered as directed by the owner’s veterinarian. Often that means at least twice every year, and horses that travel to events should get booster vaccines as often as every three months. The vaccine does not appear to protect horses from neurologic herpes. However, vaccination will reduce the amount of circulating EHV virus in equine populations, thereby lowering exposure risks. Horse owners are encouraged to visit with their veterinarians to determine the vaccination program best suited to their individual needs.
Dr. Oedekoven strongly encourages organizers and planners of equine events to seek the advice of veterinary professionals for guidance on disease prevention. Horses that have been vaccinated less than seven days or greater than 90 days before events are at higher risk for spreading EHV. In addition to consideration of standard health requirements, protocols should be developed prior to the events to address potential isolation and quarantine procedures in case of an outbreak.