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Equine Herpes Virus Outbreak
Then in early March, three possible cases of EHV-1 were reported in Ocala Florida at the World Equestrian Center, specifically Barn D. “On Saturday, March 6, a horse in Barn D with a high fever was removed from the show grounds and transported to the University of Florida for testing. Previously, two other horses originating from Chestnut Hill Farm in Ocala that had been stabled in Barn D developed high fevers after leaving the WEC property and have since tested positive for EHV-1,” Horse Sport reported.
The Florida Dept. of Agriculture reported: “A horse with neurological signs was reported by a private veterinary practitioner in Marion County on March 1, 2021. The horse subsequently tested positive for the Equine Herpes Virus (EHV-1), neurotrophic strain. As of March 3, 2021, the affected horse (index) continues to be treated in a separate isolation facility. The Division of Animal Industry placed the premises under quarantine and immediately began a disease investigation.
“A second horse stalled immediately adjacent to the index horse while at the farm was confirmed positive for EHV-1, on March 4. This second horse is not exhibiting neurologic symptoms, although it has been febrile and is being treated at a separate isolation facility.
“The index horse was housed at the World Equestrian Center (WEC) Barn D during week 7 (February 17 –21, 2021), and the second horse was housed in Barn D during week 8 (February 24 –28, 2021). The second horse left the World Equestrian Center on February 25, 2021. The Division of Animal Industry continues to strongly recommend horse owners and trainers enact strict biosecurity measures for horses that may have been stabled at WEC during the above dates. Biosecurity measures are key to preventing the spread of EHV-1 and can effectively break the cycle of transmission of the virus.
In Wellington, Florida, management was taking active measures to protect horses at the Palm Beach International Equestrian Center (PBIEC) and Equestrian Village during the Winter Equestrian Festival (WEF) and Adequan® Global Dressage Festival (AGDF). There were no reported cases of EHV-1 in Wellington at that time, according to a dispatch from Equestrian Sport Productions.
ESP was attempting to control transmission of the EHV-1 virus by restricting access to the PBIEC and Equestrian Village show grounds of horses from outside the immediate vicinity of Wellington.
“Given the seriousness of the EHV-1 outbreak in Europe (the case in Ocala was similar in nature but unrelated to the neurological strain of EHV-1 impacting Valencia, Spain, and other European countries), which has unfortunately resulted in multiple horse deaths, ESP implored everyone to do their part in order to keep their own horses safe, as well as those of fellow competitors.”
Update March 13:
Equestrian Sport Productions (ESP) management announced that the final outstanding test result for Equine Herpes Virus (EHV) has come in and is negative. The test result was reported on Saturday, March 13, 2021, for a horse that was stabled in Tent 19 at the Palm Beach International Equestrian Center (PBIEC) show grounds for the Winter Equestrian Festival (WEF).
Updates March 18:
Equestrian Sport Productions (ESP) management announces that a horse at Adequan® Global Dressage Festival (AGDF) presented with a fever on Wednesday, March 17. In an abundance of caution, the horse was tested for Equine Herpes Virus using a PCR test by an independent veterinarian. The test results should be received on Friday, March 19, and will be released as soon as possible.
Equestrian Sport Productions (ESP) management announces that there has been a negative test result for Equine Herpes Virus on Thursday, March 18, 2021, on the horse that was announced in this morning’s press release. The horse is on the Equestrian Village showgrounds for the Adequan® Global Dressage Festival.
ESP expected to modify its existing protocols regarding Equine Herpesvirus (EHV) by March 29, 2021.
The FEI issued an informative bulletin about Equine Herpes Virus.
Equine Herpes Virus is a contagious disease that affects horses. Although there are nine strains of the virus, Equine Herpes Virus-1 (EHV-1) and Equine Herpes Virus-4 (EHV-4) are most commonly seen.
The current outbreak in Europe is the EHV-1 strain.
Affected horses may suffer respiratory disease, neurological disease and abortion in pregnant mares. Young foals are also at risk and can die from the infection.
Equine Herpes Virus is found in many parts of the world and cases and outbreaks can be seen at any time of year.
Certain strains of the virus can cause severe illness in horses, which can result in their stables being placed under quarantine for several weeks so that horses cannot travel and are unable to compete.
Equine Herpes Virus can be transferred through the air from horse to horse up to distances of five metres.
Horses can become infected and bring the disease to their home stables and transmit the virus to other horses through close contact and coughing.
The virus can also be transmitted on clothing and yard equipment by people working with infected horses.
Horse transport is also a risk for disease transmission. Lorries and trailers in which infected horses have travelled may be contaminated with the virus and transmit the disease to others.
Thorough cleaning of all equine transport vehicles must be carried out between shipments. Stables must be thoroughly cleaned and disinfected between horses.
The clinical signs of Equine Herpes Virus depend on the strain of the virus affecting the horse.
Horses suffering from EHV-1 can develop a fever, respiratory disease such as coughing and clear nasal discharge.
Some horses may develop neurological signs leading to lack of coordination, weakness, difficulty in urinating and defecating and becoming recumbent (unable to stand up). Horses that are severely affected by the neurological form of the disease may have to be euthanized.
The virus is also a common cause of abortion in pregnant mares and the death of young foals.
Infected horses can develop complications such as secondary bacterial infections.
Horses showing the early signs of the disease must be isolated and examined by a veterinarian.
Clinical signs are often seen within approximately ten days of being in contact with the virus.
Since infected horses can show similar clinical signs to other diseases, your veterinarian should take nasopharyngeal swabs and blood samples for laboratory analysis in order to confirm the diagnosis.
Horses that have been in contact with the affected horse must be identified, isolated and tested for the disease.
The movement of all horses on and off the affected stables site must be restricted and strict biosecurity measures enforced. The measures include foot baths, hand disinfection, and the prevention of equipment sharing.
Disease Transmission Rate
Unlike Equine Influenza, which is transmitted between horses quickly, there is a slower transmission time for the Equine Herpes Virus.
Additionally, horses may not immediately display signs of the disease. It is necessary to test horses for EHV at intervals of several weeks to ensure that all affected horses and any in-contact horses have tested negative before horse movements can resume.
A vaccine against EHV-1 and EHV-4 is available but does not protect the horse against the neurological form of the disease.
However, the use of the vaccine can help to reduce the shedding of the virus, its transmission to other horses, and the severity of the respiratory form of the disease.
The vaccine should not be used during an outbreak at stables.
Your veterinarian will be able to advise you further on the use of the vaccine.
The FEI recommends that horses which have mixed with others are closely monitored on their return home and their rectal temperature taken twice daily.
Horses that have a fever must be examined by a veterinarian as soon as possible.
Where horses have travelled away from their home stables, strict hygiene measures should be carried out at the home stables to reduce the transmission of the virus to other horses.
It is important to make sure that horses do not share equipment such as water buckets/troughs, feed bowls, tack and grooming equipment, and that anyone working with horses washes their hands between handling horses. All vehicles used for transportation must be thoroughly cleaned between horses.
A horse displaying any signs of illness should be isolated, not leave their home yard, and be examined by a veterinarian. This also applies to any horse that has been in contact with a horse or horses that have the Equine Herpes Virus.
To keep updated on EHV-1, please visit: https://www.fei.org/stories/lifestyle/health-fitness/equine-herpes-virus-ehv-1-what-you-need-know
For more information on Equine Herpesvirus, visit the AAEP Equine Herpesvirus Resources page: https://aaep.org/guidelines/infectious-disease-control/equine-herpesvirus-resources
FEI Communications. “FEI Cancels European Mainland Events Due to EHV-1 Outbreak.” (March 1, 2021) https://horsesport.com/horse-news/fei-cancels-european-mainland-events-due-ehv1-outbreak/
Florida Department of Agriculture and Consumer Services. 2021. “EHV-1 Confirmed Cases and Quarantine Information.” (March 5) https://www.fdacs.gov/
Horse Sport Staff. “EHV-1 Reported in Ocala; World Equestrian Center Halts Ship-Ins.” (March 8, 2021) https://horsesport.com/horse-news/ehv1-reported-ocala-world-equestrian-center-halts-ship-ins/
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