ANNAPOLIS, MD – The Maryland Department of Agriculture (MDA) reports that all 25 horses in Laurel Park’s Barn 1 have tested negative for the neurologic form of equine herpesvirus (EHV-1) on a second round of tests. These tests essentially end the situation that began on Nov. 12 when a 2-year old filly became neurologic and tests proved she had the virus.  The filly was the only horse that tested positive. She was euthanized on Nov. 15.

“Today MDA and Maryland Racing Commission veterinarians examined all 25 horses in Barn 1, confirming that all appear healthy and we lifted the Hold Order,” said State Veterinarian Dr. Guy Hohenhaus.  “We are pleased and relieved that this situation ended so quickly and want to take the opportunity to remind horsemen at the track and on farms across the state to remain vigilant in their biosecurity practices to prevent this and many other illnesses in their horses."

The negative nasal swab and blood samples were taken Monday,  9 days after the last known viral exposure in the barn. If any horses were infected it is highly likely they would be detected by the aggressive testing protocol employed.  The samples were analyzed yesterday by MDA’s  College Park Animal Health Diagnostic Laboratory.  With these results, all horses in Laurel Park’s Barn 1, where the EHV-1-positive filly was stabled, have tested negative for the virus twice. No horses in the barn are showing signs of the illness. 

“This is the first time MDA has used its new EHV diagnostic capability in a real-time incident and it has proved to be accurate, effective and swift, saving critical response time and providing a valuable service to the equine community in Maryland,” said Dr. Hohenhaus. “I commend staff for their outstanding work in the laboratory and in the field helping to draw this event to conclusion.”
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The MDA placed a Hold Order on Barn 1 on Nov. 12 restricting all movement into and out of the barn, pending further testing.  The Hold Order was in place until all horses tested negative on nasal swab and blood samples after the end of a 10 day incubation period.  On Friday, Nov. 14 the Maryland Jockey Club prohibited until further notice any horses from shipping into Laurel Park except those from the Bowie Training Center on a Maryland Jockey Club shuttle.  This action was a pro-active and preventative measure taken with an abundance of caution by the Jockey Club. The EHV-positive filly was euthanized on Nov. 15.  On November 18,  samples from 31 lead ponies submitted by the Maryland Jockey Club were negative.

Equine herpesvirus causes upper respiratory infection and can lead to severe neurological disease. There is currently no known method to reliably prevent the neurologic form of EHV-1 infection. It is recommended to maintain appropriate vaccination procedures in an attempt to reduce the incidence of the respiratory form of EHV-1 infection, which may help prevent the neurologic form. Transmission occurs primarily by direct nose to nose contact or contaminated hands, equipment, feed and water. It can also be spread up to 35 feet by airborn droplets. This virus is not associated with any human health risk.

More information about equine herpesvirus and biosecurity practices can be found at www.mda.state.md.us/animal_health/diseases/ehv.php

Source: Maryland Department of Agriculture Press Release