Churchill Downs and Kentucky veterinary officials are segregating horses because of a possible outbreak of an equine respiratory virus in three barns, but no horses entered in Saturday’s Preakness Stakes (gr. I) are affected.

Rusty Ford of the Kentucky State Veterinarian’s Office told The Blood-Horse Tuesday night an “indication” of equine herpesvirus was the reason for the quarantine and said he was awaiting test results Wednesday morning that could confirm the presence of the virus.

A horsemen’s meeting was scheduled for 10:30 a.m. EDT on the Churchill backstretch to discuss the situation.

Shipping agent Paul Holthus told The Blood-Horse Wednesday morning none of the Preakness starters was stabled in the barns now under quarantine. They would be permitted to leave Louisville for Pimlico racecourse in Baltimore Wednesday morning, he said.

Expected on one of three scheduled flights is Kentucky Derby (gr. I) winner Giacomo. Holthus said horses trained by William Cesare and Steve Asmussen were not permitted to travel because “their barns are under quarantine.”

Trainer Ronny Werner confirmed Wednesday morning that his Churchill barn is under quarantine. He said only one of his horses was infected with the virus. “It started up about a week ago,” Werner said. “I’ve got 20 horses in the barn that aren’t infected, but they are affected.”

Trainer Paul McGee said his barn technically isn’t under quarantine, though he was asked “not to send any horses to the track” for training.

According to veterinarian Nancy S. Loving, writing in the June 2005 issue of The Horse magazine, equine herpesvirus is classified into five different strains. EHV-1 and EHV-4 are the strains associated with viral respiratory disease. EHV-1 is the most prevalent concern in horse populations not only because its respiratory disease is more virulent than that caused by EHV-4, but also because it can lead to viral abortion in mares or neurologic disease.

Fever and an upper respiratory infection are the most common signs of EHV-1. Infected horses may show signs of lethargy, poor appetite, nasal discharge, and a cough. An infected horse can spread the virus up to 35 feet, with a cough or snort. The virus is short-lived and susceptible to disinfectants.

Detection of EHV-1 in three horses at Turfway Park in March 2003 just days before that track’s major event, the Lane’s End Stakes (gr. II), did not disrupt the race, though track officials took several precautionary steps to ensure the health of the horses at the Northern Kentucky track.

The Turfway outbreak occurred within one barn, which was put under quarantine for 21 days. Horses shipped in to the track during that period were housed only in the receiving barn or stakes barn, and all stalls in those barns were stripped and thoroughly sanitized.

In a separate incident that same month, five horses at Penn National racecourse in Pennsylvania also tested positive for EHV-1. That outbreak led officials at Philadelphia Park and at racetracks in West Virginia to impose a temporary ban on shipping horses to and from Penn National. Two of the five horses died as a result of EHV-1.

In January and February of 2003, an outbreak of EHV-1 at the University of Findlay in Ohio led to the death of 12 horses.

More information on equine herpesvirus:
Equine Herpesviruses 1 & 4
All TheHorse.com articles on equine herpesvirus