WI: STATE VETERINARIAN EHLENFELDT: HORSE OWNERS TAKE NOTE; DANGEROUS STRAIN OF EHV-1 ON THE RISE

News Date October 13, 2009

A soon-to-be published study reports that a common virus that infects horses is increasingly taking a more dangerous form, prompting Wisconsin State Veterinarian Dr. Robert Ehlenfeldt to remind owners to protect their stock with basic biosecurity.

Equine herpes virus type 1, or EHV-1, usually causes a respiratory infection called rhino-pneumonitis. It also has a more serious, often fatal, neurologic form that strikes the horse’s central nervous system. A recent study by researchers at the University of Kentucky found that the neurologic form is increasingly prevalent.  Results of that study are to be published in the journal Veterinary Microbiology. The researchers found that only about 3 percent of EHV-1 cases were neurologic in the 1960s.  In the 1990s, over 14 percent were neurologic, and by 2006, more than 19 percent of EHV-1 cases were the more dangerous strain, they found. 

In 2006 an outbreak of this strain of the disease arrived in the United States with a shipment of horses from Germany that scattered to eight states.  Two unrelated cases were also found in a Wisconsin stable that year.

“Like a lot of viruses, this one thrives in cooler conditions, so we’re coming into EHV season,” Ehlenfeldt said.  “There’s no vaccine for this form of the disease, so biosecurity is even more important.”

EHV-1 spreads when horses in close contact cough or sneeze, and on contaminated hands, water and feed. It can cause abortion in pregnant mares and death in foals.  The neurologic strain may cause horses to be uncoordinated, unable to stand, and unable to eliminate urine and manure.  They may also have swollen, inflamed legs and hemorrhages on their gums. EHV-1 vaccines are not effective against the neurologic form.

For more information about EHV-1, visit the U.S. Department of Agriculture website.  (Contact: Donna Gilson, 608-224-5130)