The Sun-Sentinel has reported an outbreak of an undetermined equine virus at the American Grand Prix Association National Championship at the Palm Beach Polo Equestrian Club, forcing officials to cancel the show.

Four horses are reported dead from a virus suspected to be equine herpesvirus-1 (EHV-1), including rider Debbie Stephens’ horse Cosequin’s CEO. The Sun-Sentinel has reported that three farms in the Grand Prix Village, which is located next to the Equestrian Club, are in complete lockdown.

Equine herpesvirus can spread through direct contact or through the air, making it a concern where groups of horses are stabled. The clinical signs of the disease include fever, nasal discharge, and occasionally can progress to neurologic signs (including an inability to control the hind limbs and tail), and late-term abortions. Special testing is required to definitively diagnose EHV infections through virus culture of blood or nasal secretions, PCR (a DNA test of blood or nasal secretions), or serology (antibody titers).

“Safeguarding the horses in our community and the protection of the equestrian industry in Wellington is our utmost and primary concern,” Stadium Jumping Inc. President Gene Mische told The Sun-Sentinel. “We would much rather prefer to err on the side of caution than put even a single horse at risk.”

Wellington, Fla., hosts a large number of competing horses every winter, as riders migrate to the warmer weather and continuing competition.

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.