EHV-1 Outbreak: What Is EHV and What To Look Out For

November 2025 – An aggressive EHV-1 outbreak has been confirmed in the USA, linked to the World Championship Barrel Racing Finals in Waco, Texas. The virus has since spread to other states, including Oklahoma and Louisiana, with some cases developing into the neurological form (Equine Herpesvirus Myeloencephalopathy or EHM). Multiple horse events have been cancelled or postponed because of this.

Authorities have issued alerts, warning people to monitor their horses for any signs of the virus. “This virus can spread fast, it can be deadly, and the earliest signs are often so subtle they’re easy to miss. That’s why monitoring your horses right now is critical. The quicker we identify a potential case, the better chance we have to protect not only our animals, but the entire Texas equine community," Commissioner Sid Miller said.

The National Barrel Horse Association (NBHA) is implementing immediate precautionary measures to safeguard both members’ and equine health while information on this matter continues to develop.

You can check Equine Disease Communication Center (EDCC)'s link for the latest updates on the affected states and confirmed cases.

What is Equine Herpesvirus or “EHV”?

Equine Herpesvirus (EHV) is a contagious virus in horses that can cause respiratory illness, abortion in pregnant mares, and neurological damage in the form of Equine Herpesvirus Myeloencephalopathy (EHM).

What are the major or most common types of EHV?

• EHV-1: This is the most concerning strain, possibly causing respiratory illness, abortion, fever and can lead to the neurological form (EHM), which can be fatal and is characterized by hind limb weakness, incoordination, inability to stand and loss of bladder control. EHM can be life-threatening and requires immediate veterinary attention.
• EHV-3: Known as coital exanthema, it is a venereal disease that affects the external genitalia of horses.
• EHV-4: Primarily causes respiratory disease in young horses but can also lead to abortion in mares.

Lesser types of EHV are the following:

• EHV-2: Associated with immunosuppression and a type of eye inflammation called keratoconjunctivitis.
• EHV-5: Can be linked to a serious lung condition called equine multinodular pulmonary fibrosis.

EHV spreads through direct contact with infected horses or contaminated equipment, feed, and water. While many horses remain latently infected, stress can cause a flare-up and lead to serious symptoms associated with the disease.

What are the signs or symptoms of EHV in Horses?

Keep an eye out for the different signs your equine can have when infected with EHV:

Respiratory symptoms of EHV

• Fever (can be biphasic)
• Nasal discharge (serous to mucopurulent)
• Coughing
• Depression or lethargy
• Loss of appetite
• Swollen lymph nodes
• Conjunctivitis (swollen eyes)

Neurological symptoms (Equine Herpesvirus Myeloencephalopathy)

• Incoordination and stumbling
• Hind-limb weakness
• Loss of tail tone
• Difficulty urinating or urine dribbling
• Loss of bladder and/or bowel control
• Head tilt
• Inability to stand or rise (recumbency)

Reproductive signs of EHV

• Abortion, typically in the last four months of gestation
• Mares may show no other signs of illness before aborting
• Live foals born to mares infected late in gestation can be born with severe respiratory distress and die quickly

How can a horse be infected with EHV?

A horse can become infected with Equine Herpesvirus (EHV) through direct contact with an infected horse, such as nose-to-nose contact, or through indirect transmission via contaminated objects or people. The virus spreads through airborne particles from coughing, respiratory secretions, and contaminated equipment, feed, water buckets, and tack.

For mares, EHV-1 can also be transmitted through contact with aborted fetuses, fetal membranes, and fluids.

What should you do if your horse has EHV?

If your horse is infected with Equine Herpesvirus (EHV), immediately isolate the sick horse and quarantine all exposed horses. Stop all horse movement on and off the premise and limit contact between healthy and sick animals. Contact your veterinarian to confirm the diagnosis, discuss treatment for symptoms, and get guidance on the duration of quarantine and when it is safe to reintroduce your horse to other animals.

• Isolate the infected horse, away from all the other horses and animals.
• Quarantine exposed horses. All horses that were in contact with the infected horse must be strictly quarantined for a minimum of 14 to 28 days.
• Do not allow any new horses to enter the premises, and do not transport any horses off-site.
• Contact your vet right away. A veterinarian is essential for proper diagnosis, treatment, and guidance on biosecurity protocols. They can assess the severity of the case and provide specific advice.
• Do not share equipment. Keep all equipment, including buckets, feed troughs, horse tack, and grooming tools, separate for the sick and healthy horses.
• Wash your hands thoroughly with soap and water or use hand sanitizer after handling any horse, especially before moving to a different one. Change your clothes and footwear after working with the sick horse.
• Disinfect thoroughly. Clean and disinfect all surfaces, stalls, trailers, and shared equipment with a suitable virucidal disinfectant. Cleaning first with soap and water will help remove organic material and make the disinfectant more effective.
• Monitor the rectal temperature of all exposed horses twice a day and report any fever (greater than 101.5 °F) or neurological signs to your veterinarian immediately.
• Supportive care, including anti-inflammatory drugs to reduce fever, is the main treatment for uncomplicated cases. Your vet will advise on any necessary medications.

Once recovered, the horse should be rested and then gradually returned to work.

How can you prevent your horse from getting EHV?

• Practice rigorous biosecurity by quarantining new or returning horses for at least 21 days, and isolate sick horses.
• Vaccinate your horse to reduce the severity and spread of the virus. You can get EHV vaccines for horses online at Jeffers.
• Maintain strict hygiene by washing your hands and disinfecting equipment, tools, and clothing after contact with other horses.