Ocala Herpesvirus Meeting: A Veterinarian's Perspective

On Dec. 20 the state of Florida, in conjunction with the University of Florida's College of Veterinary Medicine, held an afternoon equine herpesvirus-1 (EHV-1) meeting for veterinarians, farm managers, and horse owners in Ocala, Fla., at the Ocala Breeders Sales Building. Presenters at this meeting discussed the equine herpes outbreak, including clinical signs, diagnosis, treatment, and prognosis. Veterinarians revealed quarantined locales in Palm Beach and Marion counties and how those quarantine policies are conducted. Those in South Florida that are involved in the quarantine were applauded for their efforts to quell the outbreak. Prevention was the most popular discussion.

Michael Short, DVM, equine programs manager for Florida's Division of Animal Industry, started off the meeting by discussing the chronological events surrounding the EHV-1 infections. Five horses were imported from Europe through the New York animal import station and placed on a trailer headed for Wellington, Fla. Along the trip, four more horses were picked up--three in Huntington, N.Y., and one in Darlington, Md. Upon arrival in Wellington, one of the original horses was ill. Two horses that were stabled with the index (first) case have died and the premises, J N and Company, is under state quarantine.

The horse that was picked up in Maryland had previously been sick with pleuropneumonia prior to shipment. This horse was dropped off in Wellington at Southfields Training Facility, and it became ill and died on Dec. 2. No lab tests were done. That site is under voluntary quarantine because animals were exposed to the original horse. A positive test was returned on a horse stabled at Palm Beach Equine Sports Complex, which is a part of the Southfields Training Facility, and officials are awaiting results on a second suspect case. This facility is also under a state quarantine.

Palm Beach Equine Clinic treated another one of the horses that arrived with the original shipment. A horse from Ocala who developed EHV-1 was also treated at the Palm Beach Equine Clinic and this is possibly where it became infected. This horse was found sick upon its return in Ocala after hospitalization and was immediately isolated, tested positive, and is under treatment. In Jupiter (Pinehurst Stables), another horse has exhibited neurological signs and the results from lab test are pending.

Florida officials are recommending that all horses with fever AND neurological signs be tested for herpesvirus. Veterinarians should call the state veterinarian to obtain the address for shipping samples.

Maureen Long, DVM, Dipl. ACVIM, assistant professor of large animal veterinary medicine at the University of Florida, began by stating that management of this disease is the responsibility of the horse owners and treatment is up to the veterinarians. She likened herpesvirus to a cold sore because it continues to reappear in those affected and especially those under stress. She said that, bottom line, this outbreak is no one's fault. Some of her suggestions were not to ship a horse with a fever, and to isolate shipped horses. Horses with subclinical EHV-1 can shed the virus and have no apparent clinical signs. Thirty percent might get a fever that goes unnoticed or mild respiratory signs, less develop neurologic signs, and fewer than those die. Long feels that the horse community is experiencing more of these types of outbreaks either due to better diagnostics available to veterinarians, changes of the viral strain (to which horses could be more susceptible), or possibly the global movement of horses.

Horses with EHV-1 will have a biphasic, low-grade fever (one that comes and goes over the course of several days). Once they show neurological signs they are contagious, but they will shed virus prior to any evidence of neurological disease. Some of the neurological signs include paresis or weakness of the hind limbs, an uncoordinated walk, some facial nerve signs, and dribbling urine. Those affected will require extensive treatment, and if they survive, some might have residual problems (but most do well).

Some suggestions for horse owners are to stop nose-to-nose contact, wash hands after touching horses, and do not share bits, buckets, feed tubs, or any other items that might be used by more than one horse. If you have a closed farm with no commercial work such as lessons or transporting horses in and out of your barn, you are at low risk for EHV-1. The virus is easy to inactivate using soap, bleach footbaths, and bleach water buckets and feed tubs. Pressure washers are not recommended when cleaning and disinfecting contaminated facilities.

Long gave a summary of the quarantine protocols that are being used by the state and by individual barn owners. The biosecurity protocol includes a 28-day quarantine of premises, disinfecting premises, washing hands between patients, wearing different covered booties between patients, disposing of manure (the manure must not be spread), and washing water and feed buckets. The AAEP has good biosecurity guidelines on its Web site, and your veterinarian has access to that information.

She complimented the barn owners for their diligence in enforcing a good quarantine protocol. She asked the media that was present to not cross the quarantine lines that are established to just get the story. Several entire facilities are shut down, but in some places it might be just one isolated barn that is affected. Those barns that are still transporting horses, showing, or sending horses to the racetracks are at a higher risk of encountering EHV-1. The primary disciplines that seem to be affected are show jumpers, polo, and racing. Commercial haulers are also a high risk as well as veterinary clinics. Horses will be retested prior to leaving quarantine. They must be negative for 21 days before quarantine can be lifted.

All horsemen should practice biosecurity at all times. This includes washing hands after touching every horse, not sharing feed and water buckets or equipment, washing boots or tools used by horsemen. Long explained that the rhinopneumonitis vaccines do not give protection from the neurological form of the disease, but they might help in decreasing the spread of the virus.

Short and Long took questions from the audience. Some of the questions pertained to hay and feed delivery. Veterinarians recommended haulers wash their trucks' tires and not interact with horses on any of the properties. One horse hauling company told the group that they are cleaning trailers after every trip.

Long and she said any rhinopneumonitis vaccine could be used. Someone asked about holding an endurance ride in north Florida and what should be done about horses coming from the West Palm Beach area. It was suggested to organize a protocol with the state veterinarian regarding housing of the horses and using biosecurity measures when evaluating the horses throughout the ride. Some event officials might request health certificates from your veterinarian stating that your horses are not from a barn with EHV-1 or suspected EHV-1. This request is up to each individual event coordinator.

In summary, this outbreak has everyone in Florida who deals with horses on alert. The financial effect will be widespread. From the Thoroughbred sales to the gasoline sold to commercial horse haulers, everyone will be hoping the strict quarantine measures are going to be the last they see of this disease in Florida. As of Dec. 26, there were five EHV-1 deaths, nine cases were confirmed as EHV-1, and there were ten quarantined premises. Of the nine confirmed cases, seven are in Wellington, one is in Ocala, and one in Indiantown. The ten quarantined premises are as follows: J N Stables in Wellington, S & L Farms in Wellington, Equine Services Ltd in West Palm Beach, Palm Beach Equine Sports Complex in Wellington, Palm Beach Equine Clinic in Wellington, Reid & Associates in Loxahatchee, Pinehurst Stables in Jupiter, Tuxedo Farms in Morriston, Payson Park in Indiantown, and Victory Lane in Wellington.

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.

About the Author

Erin Denney-Jones, DVM

Erin Denney-Jones, DVM, is an FEI veterinarian and owner of Florida Equine Veterinary Services, in Clermont, Florida. Her interests and practice areas include chiropractic care, sport horse medicine, reproduction, general medicine and surgery, and preventive care including wellness programs, vaccinations, parasite control, and dentistry.

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