Newsdate: Thursday, June 29, 2023 - 11:00 am
Location: NASHVILLE, Tennessee

The Tennessee State Veterinarian is advising horse owners of cases of Equine Herpes Virus One (EHV-1) in a neighboring state.

Biosecurity sign on a horse farm.

While there is no way to eliminate all risks of disease when comingling horses, vaccinations and good biosecurity measures reduce the risk on the farm and while at competitions.
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Last week, two horses at horse show in Lexington, Va. tested positive for EHV-1. EHV in all forms is highly infectious and found worldwide. EHV-1 can cause upper respiratory disease, neurological disease, abortions and neonatal death.

“For the general horse population, there isn’t cause for alarm, but I urge owners to be aware of practices that help keep horses healthy,” State Veterinarian Dr. Samantha Beaty said.

“Consult with your veterinarian to determine appropriate vaccines for your herd. If a horse has been exposed to EHV, such as in the same area in a barn or in a show ring together, I strongly advise quarantining for a minimum of 14 days and up to 30 days in cases of direct contact. This helps prevent the spread of disease and protects others, particularly if you’re attending shows or group trail rides.”

Equines coming in from other states must have a current certificate of veterinary inspection (CVI) to enter Tennessee. This health certificate requires that a veterinarian inspect each equine for signs of disease to ensure that it appears healthy for movement, and it is valid for 30 days. More information can be found online at www.tn.gov/agriculture/businesses/animals/animal-health/equine-passport.html.

While there is no way to eliminate all risks of disease when comingling horses, vaccinations and good biosecurity measures reduce the risk on the farm and while at competitions. Do not share buckets, brushes, halters, bridles, bits, or other equipment. Contact your veterinarian if you notice any signs of illness in your animals, officials said.

Herpes viruses are viruses that are commonly found in horses in nearly every country in the world. Fortunately, many horses that have been infected with the virus have no serious side effects. It is unknown what causes some horses to develop the serious neurological forms that may be fatal.

The disease is easily spread and typically has an incubation period between 2-10 days. Respiratory shedding of the virus occurs for 7-10 days, but may last longer in infected horses.

Symptoms

• Fever
• Nasal discharge
• Incoordination
• Hind limb weakness
• Loss of tail tone
• Lethargy
• Urine dribbling
• Head tilt
• Leaning against stationary fixtures, such as a fence, to maintain balance
• Inability to stand

Prevention

Horses suspected of having EHV infections should be examined by a veterinarian and tested for virus shedding. Infected horses should be isolated immediately and all contact with other horses should be avoided. Exposed horses should also be isolated.

Two main methods of prevention can be implemented to avoid EHV outbreaks. Vaccinations and biosecurity protection are both important in preventing EHV diseases and in reducing exposure.

The goal of vaccination is to induce resistance to infection prior to exposure by producing a strong and durable immune response without inducing clinical signs of the disease in the horse. Several vaccines are available for protection against both respiratory disease and abortion as a result of EHV-1 infection, but currently no equine vaccine is licensed that has a label claim for protection against the neurological strain of the virus.

Biosecurity measures include doing everything possible to reduce the chances of an infectious disease being carried onto your property by people, animals, equipment, or vehicles, either accidentally or on purpose. Anything that touches an infected horse and secretions shed by sick horses have the potential to transfer pathogens to other horses.

The immediate separation and isolation of identified suspect cases is key to disease control. Ideally, a person caring for a sick horse should not also work with or be around healthy horses. If this is impractical, it is recommended that healthy horses should be worked with first and sick horses last.

Wearing disposable gloves and changing them between horses or the use of hand sanitizers between horse contacts are alternative recommendations. Thorough cleaning and disinfection of foot wear between entry into barns and stalls can also minimize risks of disease spread.

Herpes viruses are susceptible to many disinfectants, including a 1:10 dilution of bleach in water. Both alcohol and bleach disinfectants are inactivated by organic matter, so all soil and manure should be cleaned away before using these products. Soap and detergent can be used effectively before applying a disinfectant.

A disinfectant that retains activity in the presence of organic matter is recommended In barn environments where organic material cannot be completely eliminated. Phenolics, such as 1 Stoke Environ or SynPhenol-3, or accelerated hydrogen peroxide products, such as Virkon, have this property. Always follow manufacturer's recommendations when using these products.

Follow the Equine Disease Communication Center for current disease outbreaks at equinediseasecc.org/alerts.

Press release by Tennessee State Commission for Animal Health