The source of the current outbreak of neurologic illness in Wellington, Fla., has been traced back to a shipment of 15 horses imported from Europe the last week of November. The horses were housed together at a quarantine facility in New York. One of the 15 died after being shipped to California and was diagnosed with equine herpesvirus-1 (EHV-1). Five of the horses shipped to Florida, two of which now have neurologic signs. The whereabouts of the other nine horses are unknown at this time, but they are being tracked down by federal officials.

Three other horses in Florida have died in association with the outbreak.

Starting from the announcement that a high-performance horse show in Wellington was cancelled and one of its stars euthanatized from what appeared to be a contagious virus, the local equestrian community has scrambled to impose voluntary quarantines and deal with mandatory stop-movement orders. Veterinarians also are vaccinating or boostering many horses against equine herpesvirus.

Scott Swerdlin, DVM, MRCVS, a veterinarian with the Palm Beach Equine Clinic in Wellington, said today (Dec. 15) that most horse owners are vaccinating their horses and keeping equine movement to a minimum. Swerdlin estimates that 4,000 horses have been vaccinated in the past 48 hours.

The three horses were confirmed dead due to a viral disease strongly suspected to be neurologic EHV-1. Test results to confirm the disease on the dead animals, as well as those exhibiting neurologic signs, are expected either tonight (Dec. 15) or tomorrow.

Researchers with the University of Kentucky are currently performing both PCR and virus isolation tests on whole blood and nasal swab samples, according to Mike Short, DVM, equine programs manager for Florida’s Division of Animal Industry.

“We’ve not seen any clinical signs outside of two areas here in Wellington, and we’re managing both of those, working with the practices and veterinarians,” Short said. “We’ve certainly got our fingers crossed that we’ve got it under control, but time will tell.” (EHV typically has an incubation period of two to 10 days.)

“We’re requesting that all horsemen in the Wellington take temperatures of their horses twice a day, and if horses are displaying a temperature of over 102, to contact their veterinarians,” Swerdlin said.

“State of Florida Department of Agriculture is being very aggressive and is staying on top of everything,” Swerdlin added. “All the vets are being very aggressive, and the horse owners have been very cooperative and very understanding.”

The possibility of an outbreak came to many horse owners’ attention when it was announced that Cosequin’s CEO, a Grand Prix show jumper ridden by Debbie Stephens, had died on Sunday (Dec. 10) due to an unknown, apparently contagious illness.

According to Swerdlin, the five horses that originated in Europe and ended up in Florida are in isolation and being evaluated. Two have shown neurologic signs and are currently being treated. One of these horses (the suspected index case–the case from which all other Florida cases trace back) was stabled next to Stephens’ horse on Dec. 7.

Short will be addressing area veterinarians this evening, and a USDA veterinarian will be hosting a forum on EHV at the Palm Beach Polo Equestrian Club this Saturday (Dec. 16) for area equestrians, veterinarians, and members of the general public.

Because EHV-1 can spread through direct contact or through the air, the disease is a concern where groups of horses congregate. The clinical signs of EHV-1 include fever and nasal discharge, and more rarely, neurologic signs (including an inability to control the hind limbs and tail) and abortions. Scientists definitively diagnose EHV-1 infections on virus culture from blood or nasal secretions, PCR (polymerase chain reaction test, a DNA test of blood or nasal secretions), or serology (blood antibody titers).

For more information on EHV-1, check out our free PDF library of EHV-related articles including images, or all our archived EHV-1 articles on TheHorse.com