Monday, January 1, 2007

Equine Herpes Virus Update

Veterianians are optimistic that Florida's outbreak of Equine Herpes Virus Type 1 (EHV-1) has been contained. No new horses outside quarantined areas have been confirmed with the disease since before Christmas, and, with strict biosecurity measures in place, the vets believe that the outbreak has run its course.

All is not yet back to normal in Wellington, however. To date, 10 facilities are under state-mandated quarantine, up from eight before Christmas. A sixth Florida horse was euthanized on Friday, bringing the total from this outbreak to seven. (An additional sick horse had been shipped to California where he died.) The State of Florida counts 12 infected horses, six of which exhibited neurological symptoms. An additional six horses have neurological symptoms, but have not been definitively diagnosed.

(Read Florida's statistics here.)

Residents say that the area around Palm Beach Equestrian Center looks a bit eerie, with yellow caution tape strung around the quarantined barns and few horses or people in evidence. All barns in the Wellington area (whether they have a case or not) are being advised to follow strict biosecurity measures. These measures include stepping in a bleach footbath when entering or leaving a barn, washing hands between horses, not sharing equipment and confining dogs, goats and any barnyard animals that might inadvertently spread germs. (Read more about it here.) Even manure is being quarantined.

Polo tournaments, scheduled to begin this weekend in Gulfstream and at Outback, will be the first major equestrian competitions in the area. Polo organizers are determined to have these tournaments run well and safely, and are asking players and grooms to cooperate by instituting strict hygenic protocols. These protocols include asking grooms to use hand sanitizer between handling horses at games and to refrain from "unnecessary" socializing. Those who work multiple games for different players are being asked to go home, shower and change their clothes between jobs. Players, grooms, club owners and managers will convene Tuesday night at the Player's Club to review biosecurity procedures and learn the latest news and plans.

Despite the optimism of Wellington's vets, there are some notes of caution. The first is that the last horse to be diagnosed in Florida has no known link to the "index" horse. Florida's state vet is confident that a link will be found and that the horse probably contracted the disease through a handler. It remains possible, however, that there is still some carrier outside of the quarantined barns.

The second disquieting news is the apppearance of two new neuropathogenic EHV-1 cases, one in California, the other in Connecticut. The Connecticut horse shipped from his home in Vermont to Fairfield Equine in Newtowne for arthroscopic surgery. While there, he spiked a fever. Tests came back positive for neurological EHV-1. Fairfield's vets are trying to determine how and where this horse may have contracted the disease. So far, there is no known link with the "index" case.

Separately, on December 28, a three-year old in training at Golden Gate Park in California exhibited "neurological discomfort" after a training session, and was subsequently tested and diagnosed with neuropathogenic EHV-1. This horse is being treated at a veterinary clinic, and three tracks in the San Francisco Bay area are now under quarantine (Golden Gate Park, Bay Meadows and Pleasanton.) Horses from these three tracks are allowed to ship to one of the other tracks, but they are not allowed to go anywhere else.

Like the horse in Connecticut, California's second positive horse has no known connection to the index horses. (Two California fillies were initially thought to be positive after they shipped with one of the original sick horses. They were restested, however, revealing that, although they did have EHV-1, it was the more common, mild respiratory, rather than the dangerous neuropathogenic strain. Both are recovering nicely.)

What does this mean for horse owners? One disturbing possibility is that the neurpathogenic strain of the disease, which appears to be poorly controlled by vaccination, is becoming more common. Equine herpes virus is an organism that can lie dormant in a horse's body for years, only to surface during times of stress, when, although he may not become actively ill, he can "shed" the virus, passing it on the those around him. If this dangerous strain is proliferating, there may be a growing reservoir of silent carriers in the equine population. The likely result is that we can expect to see more outbreaks of this type in the future. (Read some technical information about this here.)