Equine Herpes Virus (EHV-1) Recommendations
What is EHV-1?
Equine Herpes Virus-1 is a contagious viral disease that is most commonly known as Rhinopneumonitis (Rhino). This virus causes fever, respiratory disease, abortion in pregnant mares, and neurologic disease (weakness, lack of coordination, and sometimes paralysis). Recently, Florida has had an outbreak of the neurologic form of EHV-1. This virus is spread in secretions through the air (30-40 ft), by direct contact, and indirect contact (hands, buckets, boots, etc). The Florida outbreak has resulted in 12 infected horses, 6 associated deaths, and quarantine of 10 premises. There is also a confirmed case of EHV-1 in a Vermont horse that underwent surgery at a veterinary clinic in Connecticut. They believe the horse contracted the infection while at the hospital.
Vaccination and EHV-1:
The Flu/Rhino vaccine that was given in the fall is a killed vaccine that has some protection against EHV-1 and EHV-4, but unfortunately no vaccine gives complete immunity. Currently there is no vaccine available that prevents against the neurologic form of EHV-1.
At this time, we are following Cornell University’s College of Veterinary Medicine guidelines and are recommending the administration of a modified live vaccine called Rhinomune (Pfizer) to open herds and barns. This vaccine will need a booster in 3-4 weeks.
An open herd/barn is a farm where horses are coming on and off the farm on a daily/weekly basis (outside horses using the indoor, going back and forth to other barns for lessons, showing, traveling between state lines, attending clinics, etc.).
Reasons to vaccinate with Rhinomune:
o Vaccination decreases the severity of the disease and decreases the mortality from EHV-1, increasing the chance of survival.
o Horses vaccinated with Rhinomune that become ill will not shed the virus in their nasal secretions: this significantly decreases the spread of the disease, and will help prevent an outbreak in the barn.
People who opt not to vaccinate:
o Non-vaccinated horses should not travel to open barns or show grounds that have the potential to have EHV-1 carriers.
o Barns with non-vaccinated horses should follow strict quarantine protocols outlined below. This includes horses that come just for a daily lesson.
o Non-vaccinated horses that become ill will have higher likelihood of mortality and will have a much higher index of viral shedding, greatly increasing the risk of infecting other horses.
o The best tactic to protect non-vaccinated horses is to prevent any possibility of exposure to sick animals
Transport of Horses and New Arrivals:
Transportation:
o Never ship a horse with a fever. The horse should have a normal temperature <101.5 for five days prior to shipment.
o Horse should have a health certificate and physical examination from a veterinarian prior to shipment.
o All horses should be current on vaccinations. If the horse is being shipped to or from an area that has the possibility of exposure to EHV-1, vaccination with the modified live Rhinomune is strongly encouraged.
New Arrivals/Quarantine:
o Quarantine in an area that is 30-40 feet away from all other horses and with no access to the public. This area should have its own mucking equipment, brushes, blankets, etc. This horse should be dealt with last when cleaning the barn. All clothes, boots, and hands should be cleaned prior to working with other horses. Use a 1-20 dilution of bleach to water for foot baths and wash hands with plenty of soap and hot water.
o EHV-1 is contagious to other horses while the infected horse has a fever and for 14 days following the last day with a fever. Therefore, all horses should be quarantined for at least 15 days upon arrival.
o Monitor temperature daily. If >101.5 please call our clinic.
o It is also recommended that all questionable horses have a titer and nasal swab taken upon arrival and at 14 days post arrival to evaluate for EHV-1.
Overall, the practice of vaccination and biosecurity is important to prevent disease. If you have any concerns regarding your barn or your horse please call VLAC at 802-893-6800.
Vermont Large Animal Clinic
1054 Lake Road
Milton, VT 05468
802-893-6800