equine herpes virus | Horse Racing Free Tips

Six Tips To Prevent And Treat Equine Herpesvirus From Hagyard’s Dr. Nathan Slovis

Equine Herpesvirus (EHV-1) can cause respiratory disease, abortions and neurological disease. Transmission occurs via the respiratory system, with droplets of the virus being spread by mucus via snorting, coughing and human contact.

If you are in a high-risk area where there's a greater incidence of EHV-1 cases, the following tips may help ensure the horses in your care are protected from infection. These precautionary strategies come directly from Dr. Nathan Slovis, DACVIM, at Hagyard Equine Medical Institute. As an Internal Medicine Specialist and the Infectious Disease & Biosecurity Director, he has implemented the current Infectious Disease and Equine Emergency Response Programs at Hagyard.

Consider sharing these strategies with clients who have horses in high-risk areas.

Start monitoring your horse's temperature twice daily. Even if your horse has not been exposed, start recording their temperature now to understand what their normal baseline temperature is. A horse's temperature will usually spike prior to shedding significant amounts of the virus, and typically anything greater than 101.5°F should be considered a fever. If a fever is noted, you should isolate the horse to the best of your ability until a veterinarian can assess. It is recommended that any horse with a fever have both a whole blood sample and nasal swab submitted for PCR assessment for EHV-1 and EHV-4.
Limit exposure to any stressful situations that are not necessary. Examples include elective surgeries and other medical procedures. Minimizing stress will help protect the immune system so it can better fight off infection.
If your horse requires the use of corticosteroids, either systemically or intraarticularly, consult your veterinarian to see if it is feasible to stop administration. The continued use of corticosteroids can suppress the immune system and could hinder their ability to effectively fight off an infection.
Increase biosecurity measures since humans can inadvertently spread the infection on their hands, grooming equipment, etc. EHV-1 can survive on inanimate objects like halters, lead ropes, and tack, but is easy to kill on surfaces with disinfection. Therefore, these simple biosecurity measures can help stop the spread:

Wash or sanitize your hands between interacting with each horse.
Take care when filling water buckets and feed tubs – neither the hose nor the feed scoop should have contact with the bucket or tub.
Minimize the use of shared equipment, disinfecting tack (bits, bridles, etc.) between horses. Items like water buckets and feed tubs should not be shared.
There are a multitude of safe and effective disinfectants available. A few I recommend are a 1:4 ratio of bleach to water, or accelerated hydrogen peroxide-based disinfectants (like Rescue™) since they are safe for both human and animal use.

Keep your horse up to date with their EHV vaccine schedule. If you horse has not been vaccinated against EHV three months prior to travelling into an area that has a high incidence of EHV, then I would recommend vaccinating your horse. If you are in a high-risk area, consult your veterinarian about the use of vaccines that have a high antigenic load for herpes virus so you can get a robust immune response. Remember, there is no vaccine on the market that can prevent the neurological form of EHV-1. The goal of vaccinating is to reduce the severity of clinical signs and reduce shedding of the EHV-1 virus if a horse does get sick.
Some inactivated vaccines with the highest number of antigens for virus neutralization include Calvenza®, Pneumabort-K® and Prodigy®. Other vaccines like Rhinomune® are a modified live vaccine, and also have a high virus neutralization response.

If your horse is exposed or gets sick, contact your veterinarian to see what course of action they recommend. As mentioned, diagnosis requires the detection of the virus from either whole blood or nasal swab samples via PCR testing. If you are in a barn with a horse that has EHV-1, the use of the antiviral drug valacyclovir may decrease virus shedding and may help your horse from acquiring the infection. Veterinarians have also discussed the use of lysine to theoretically reduce viral replication. Horses can be administered safely 12 grams orally once daily in their feed. This has not been proven to prevent neurological forms of EHV-1.

In the neurologic form of EHV-1, the virus interacts with the blood vessels that supply the spinal cord. This inflammation in the blood vessels can cause a stroke-like event (blood clot), resulting in decreased blood flow to that portion of the spinal cord. To potentially prevent this from happening, veterinarians may prescribe anticoagulants like aspirin and/or heparin to prevent this from happening if your horse becomes clinical.

To learn more about Equine Herpesvirus, Dr. Slovis recommends referring to the American Association of Equine Practitioners (AAEP) website for accurate information and resources.

EHV-1 Outbreak In Europe Improving; Now Found Stateside

Europe has recently experienced one of the worst outbreaks of equine herpes virus (EHV-1) in decades. The neurologic form of the disease has forced the cancellation of international competitions in 10 European countries, including France, Spain, Portugal, Belgium, Italy, Austria, Poland, the Netherlands, Germany and Slovakia. The cancellations remain in place until March 28.

The initial case of EHV-1 was confirmed at the CES Valencia Spring Tour showjumping competition; 83 of the 752 horses at the venue showed clinical signs and are currently being treated for the disease. Six horses have died. An additional 15 horses are being treated at off-site equine clinics.

All horses that had been in Valencia since Feb. 1 are blocked in the Fédération Equestre Internationale (FEI) database. They cannot compete in any FEI-sanctioned event until they complete EHV-1 testing requirements. The FEI is the governing body for international equine competitions. The USDA's Veterinary Services Department has no current international movement restrictions in place.

In the United States, one 8-year-old mare in Ocala, Fla., was confirmed infected with EHV-1 on March 1 and placed in isolation. Florida Animal Health officials have implemented biosecurity protocols and are monitoring the situation. Horse owners and caretakers are reminded to take precautions before introducing new horses to an existing herd.

Equine Herpes Virus-3 Confirmed In Icelandic Herd Closed To The Outside World For Centuries

Prior to 2021, only three strains of equine herpes virus (EHV) had been confirmed in Icelandic horses living in their native country, which has been a closed herd for more than 1,000 years. Now, four strains have been reported to affect the native population: EHV-2, EHV-4, EHV-5 and EHV-3, the newest strain to be detected.

Scientists had previously speculated that the absence of EHV-1 in Icelandic horses suggested that the virus was not as common in Medieval Europe as it is today. However, with confirmation that EHV-1 does exist in the closed herd, it appears that the virus was common in horses in Europe in the 9th or 10th Century.

EHV is a family of viruses: EHV-1 can case neurologic problems, respiratory disease, abortion, neonatal death. EHV-4 causes nonfatal respiratory disease in foals and EHV-3 causes venereal disease that doesn't affect fertility.

Drs. Lilja Thorsteinsdóttir, Gunnar Örn Guðmundsson, Höskuldur Jensson, Sigurbjörg Torsteinsdóttir and Vilhjálmur Svansson took samples from a 3-year-old Icelandic mare that had blisters on her vulva. Testing was positive for EHV-3.

EHV-3 is non-invasive; lesions typically heal in 10 to 14 days. Infected horses may be dull, have a fever or go off their feed.

Researchers speculate the appearance of the new viral strain in the closed population may be connected to the growing popularity of Icelandic horses, which has led more horse people to travel to the country and interact with the population of Icelandics there.

Read the communication here.

Report: 18 Horses Ill As EHV-1 Sweeps Through Canadian Riding Stable

Staff at Venturing Hills Equestrian, a riding stable in Luskville, Quebec, Canada, have been working around the clock to try to save the farm's horses, which have been affected by the neurologic form of the equine herpes virus (EHV).

There are multiple strains of the equine herpes virus, including EHV-1, which can cause respiratory disease, abortion, neonatal death or neurological disease. Some horses exposed to the virus will develop neurologic signs. There is no cure for the neurological symptoms associated with EHV-1.

On Feb. 3, a healthy 5-year-old horse that lived at the farm began stumbling when he walked. His symptoms worsened and he was euthanized later that day. Samples the attending veterinarian had taken were positive for EHV-1. The second horse that died from EHV-1 was a 20-year-old horse on Valentine's Day. Both horses had been vaccinated for EHV.

Currently, 18 horses are sick, two are dead and five remain healthy. To try to keep the remaining horses disease free, staff has completely quarantined the healthy horses from the ill horses by building stalls on the property. They have also instituted biosecurity measures like limiting the people who see the infected horses, wearing hazmat suits and steaming hay nets to kill the virus.

Owner Rae Becke believes a new horse that arrived at the facility on January 15 brought the virus with him from Toronto. She later learned that three horses at the horse's former facility had died from the virus on Jan. 29. Becke was never informed of the situation, so the new horse was turned out with Venturing Hills' equine residents.