Herpes in horses: prevention & treatment

What is herpes in horses?

Equine herpes, also known as equine herpesvirus (EHV), equine herpes or rhinopneumonitis, is a contagious viral disease caused by different types of equine herpesvirus. EHV-1 and EHV-4 are particularly common and can cause different courses of the disease. While EHV-4 mainly causes respiratory infections, EHV-1 can lead to respiratory diseases as well as miscarriages (viral abortion of the horse) and severe neurological disorders (neurological herpes). Transmission occurs through direct contact or droplet infection and represents a considerable health risk for horse herds.

➡️ Video tip: In this video you will learn all about the different types of EHV, such as EHV-1 and EHV-4, the most common symptoms in horses, such as respiratory infections, abortions and neurological disorders, as well as the transmission routes. Learn why the virus is so contagious and what measures horse owners can take to prevent it."

Herpes - Types in horses

Equine herpesvirus (EHV) is a group of herpesviruses that can infect horses and cause various diseases. The most common types are

• EHV-1: Responsible for respiratory infections, neurological diseases (such as paralysis) and abortions in pregnant mares.
• EHV-4: Mainly causes respiratory diseases, but is less aggressive than EHV-1.
• Other types of EHV: Less common, but also relevant for specific diseases.

These viruses are also known as rhinopneumonitis and pose a major threat to horse populations worldwide.

How common is herpes among horses?

Equine herpesvirus is extremely contagious and spreads through direct contact between infected and healthy horses. It can also be transmitted indirectly via contaminated objects such as water troughs, feed bowls and equipment. Competitions and events often pose a high risk of spreading the virus, which is why strict hygiene measures are required.

Herpes symptoms

The symptoms of herpes in horses depend on the type of herpes virus affected and can vary:

1. Respiratory form (mainly EHV-4, less frequently EHV-1)
   • Fever (up to 41°C), often in two episodes
   • Cough
   • Nasal discharge (clear to purulent)
   • Swollen lymph nodes
   • Fatigue and reduced performance
2. Neurological form (EHV-1, more rarely EHV-4)
   • Unsteady gait (ataxia)
   • Weakness or paralysis of the hindquarters
   • In severe cases, inability to stand
   • Urinary and defecation disorders
3. Reproductive form - viral abortion (EHV-1)
   • Miscarriages in pregnant mares, often in the last third of pregnancy
   • Stillbirths or weakened foals that die shortly after birth

Transmission of herpes in horses

Herpes in horses can be transmitted in various ways, both through direct contact and via contaminated objects.

As the virus can survive in the environment for several weeks, strict hygiene measures and quarantine are crucial to prevent it from spreading

How long is EHV contagious?

‍The herpes virus in horses is contagious over a long period of time. Horses can excrete the virus over a period of several weeks to months after infection, even if they no longer show symptoms. This long infection period makes the containment of EHV outbreaks considerably more difficult. Horse owners should therefore resort to strictly monitored quarantine measures and regular testing to ensure that no virus shedders go undetected.

Diagnosis of equine herpesvirus (EHV)

Procedures and tests to detect a herpes infection

‍Diagnosis of equine herpesvirus (EHV) is important to detect infections early and stop the spread. There are various tests that are used to identify an EHV infection:

• Polymerase chain reaction (PCR): This is the most precise test for detecting EHV. Nasal swabs or blood samples are used to detect the genetic material of the herpes virus in the horse. PCR is a fast and accurate method to diagnose an infection.
• Virus isolation: Here, the virus is multiplied from sample material in cell cultures. This method is more time-consuming, but it provides additional information about the viral load.
• Serological tests: These tests measure antibodies in the blood that may indicate an EHV infection. A significant increase in the antibody titer in consecutive samples indicates an active infection.

When should a vet be consulted?

‍Avet should be consulted as soon as typical herpes horse symptoms appear. These include

• Fever without recognizable cause.
• Respiratory symptoms such as coughing, nasal discharge and breathing problems.
• Neurological symptoms, including unsteady gait (ataxia), paralysis and coordination disorders.
• Reproductive problems such as sudden abortions in pregnant mares.

Early diagnosis and treatment are crucial to minimize the risk to the horse population. Timely consultation with a veterinarian is essential to control the symptoms of EHV infection and prevent the spread of the herpes virus in horses.

Treatment options for equine herpesvirus (EHV)

➡️ Video tip: Treatment options for an EHV infection! Find out how you can treat the equine herpes virus symptomatically - from anti-inflammatory medication and fluid therapy to caring for horses with neurological symptoms. We show you how you can contain the spread of the virus and protect your horses through quarantine and hygiene measures in the stable.

Symptomatic treatment: medication and care

‍Treatment of equine herpesvirus (EHV) focuses on alleviating the symptoms, as there is no specific antiviral therapy. Comprehensive management can positively influence the course of the disease:

• Anti-inflammatory medication: The administration of non-steroidal anti-inflammatory drugs(NSAIDs) helps to reduce fever and relieve inflammation and pain. These medications can improve the well-being of horses with equine herpes virus.
• Fluid therapy: Ensuring sufficient fluid intake to prevent dehydration in affected horses is particularly important.
• Rest and stress reduction: The horse's environment should be calm to minimize stress on the immune system and allow optimal regeneration.
• Care of neurologically affected horses: Intensive care is required for horses showing neurological symptoms caused by the equine herpes virus. This includes assistance with getting up, walking aids and monitoring of bladder and bowel function.

Quarantine and hygiene measures in the barn

‍Inorder to prevent the spread of equine herpesvirus, it is crucial to comply with quarantine and hygiene measures:

• Isolation of infected horses: Horses with equine herpes should be separated from healthy horses immediately to minimize the risk of infection.
• Limiting the movement of people: access to the barn should be restricted to necessary personnel who follow specific protective clothing and hygiene measures.
• Disinfection: Regular disinfection of feeding troughs, drinking troughs, cleaning utensils and other shared objects is essential to prevent the spread of the virus.
• Hand hygiene: Careful washing and disinfection of the hands before and after each contact with horses prevents indirect transmission.
• Health monitoring: Regular measurement of the body temperature of all horses in the herd for early detection of fever or other herpes horse symptoms.

Consistent quarantine, hygiene and symptomatic treatment can reduce the risk of the spread and severity of EHV infections.

Prevention and protection against equine herpesvirus (EHV)

➡️ Video tipDr. Christine Fuchs reports on the severe herpes outbreak in Valencia 2021, explains EHV types and gives important prevention and crisis tips. A must for horse owners and equestrians!

Recommended vaccinations against herpes: benefits and limitations

‍EHV vaccination is an essential part of prevention:

• Advantages: Vaccinated horses excrete fewer viruses in the event of an infection, which reduces the risk of infection for other horses. In addition, the severity of herpes horse symptoms can be reduced.
• Limits: Vaccination does not provide complete protection against the herpes virus in horses. Therefore, the combination of vaccination and hygiene measures remains crucial to control the outbreak.

Stable management and measures to reduce the risk of infection

‍Sophisticated barn management makes a significant contribution to reducing the risk of infection with EHV:

• Quarantine new horses: New horses or horses returning from shows should be isolated and tested for EHV prior to contact with other animals to minimize potential sources of infection.
• Limiting the movement of people: Access to the stable should be limited to essential personnel. Protective clothing and hygiene rules for all persons who come into contact with the horses help to keep the virus at bay.
• Health monitoring: Regularly measuring the body temperature and monitoring the health of all horses in the herd enables early detection of herpes horse symptoms such as fever.

Hygiene measures to prevent infection

➡️ Video tipHygiene in the stable: prophylaxis and emergency plan! In this video, Dr. Henrike Lagershausen, veterinarian at the German Equestrian Federation, shows you how you as a stable operator or horse owner can ensure optimum hygiene in the stable. Learn everything from simple but important measures such as the correct disinfection of shoes to emergency plans in the event of disease outbreaks. Protect your horses through consistent prophylaxis and be well prepared for emergencies!

‍Strict hygiene measures are crucial to prevent the spread of the herpes virus in horses:

• Isolation of sick horses: Horses with a confirmed EHV infection should be separated from healthy animals immediately to minimize the risk of infection.
• Disinfection of equipment and surfaces: All shared items such as feeding troughs, drinking troughs, grooming equipment and stable surfaces should be cleaned and disinfected regularly. This significantly reduces the spread of herpes in horses.
• Hand hygiene: Careful washing and disinfection of the hands before and after contact with horses helps to reduce the risk of indirect transmission of the equine herpes virus.

With the right combination of hygiene, vaccinations and effective stable management, the risk of EHV infection can be significantly reduced.

Herpes vaccination for horses: What you need to know

The equine herpes vaccine is a protective vaccination against the equine herpes virus (EHV). It is intended to reduce the risk of infection and mitigate the course of the disease.

Which virus types does the vaccination cover?

The vaccination protects against the two most important herpes viruses:

• EHV-1 (responsible for respiratory infections, neurological symptoms and miscarriages)
• EHV-4 (main cause of respiratory diseases)

Aim of the herpes vaccination

‍Vaccination cannot completely prevent infection, but it does help,

• reduce viral replication in the body,
• alleviate the severity of the symptoms,
• reduce the risk of miscarriages in pregnant mares,
• to contain the spread of the virus within a group of horses.

Timing and frequency of vaccinations

‍The EHV vaccination requires a basic immunization consisting of two vaccinations four to eight weeks apart. A booster vaccination is then recommended every six months to maintain protection against the equine herpes virus; these vaccination intervals are important to continuously strengthen your horse's immune system and minimize the risk of infection. Horses that take part in competitions or are kept in larger herds will particularly benefit from regular vaccination.

‍Efficacyand protection through vaccination

‍The EHV vaccination does not offer complete protection against infection, but can significantly mitigate the course of the disease.

• Vaccinated horses excrete fewer viruses, which reduces the risk of infection for other horses.
• Vaccination helps to alleviate the severity of symptoms such as respiratory and neurological signs.
• The spread of the virus within a herd is contained, which is particularly beneficial for stables with many horses.

Costs and legal framework

‍Thecost of an EHV vaccination varies depending on the region and veterinary practice. Horse owners should expect annual vaccination costs of approx. 100 to 120 euros.With regard to the legal framework, there is no general vaccination requirement for all horses. However, depending on the country and organization, special regulations apply to competition horses, which are regularly updated, and it is important to find out about the current regulations and develop the best vaccination strategy for your horse in consultation with your vet.

How long can the herpes vaccination be delayed in horses?

The herpes vaccination (EHV vaccination) should ideally be given every six months in order to maintain the best possible protection. Slightly exceeding the vaccination interval is usually not a problem, but too long a delay can impair vaccination protection.

Recommended tolerance period for a booster vaccination

• A short delay of a few weeks is usually still acceptable, as the immune protection does not completely wear off immediately.
• However, if the vaccination is delayed for several months, the protection can weaken to such an extent that a new basic immunization (two vaccinations at intervals of 4-8 weeks) is necessary.

Effects of late vaccination

• Protection against severe courses of the disease may diminish.
• Competition horses could be excluded from competitions due to stricter regulations by the organizers.
• The risk of miscarriage increases in pregnant mares if the vaccination is not boosted in good time.

What to do if the vaccination has been delayed?

• If the refresher was only delayed by a few weeks, it is usually sufficient to catch up as soon as possible.
• If the last vaccination was well over six months ago, the vet should decide whether a new basic vaccination is necessary.

It is advisable to adhere to the recommended vaccination intervals to ensure the best possible protection for the horse and its herd.

Herpes in horses: In summary

Equine herpesvirus (EHV), also known as rhinopneumonitis, is a serious threat to horses worldwide. The two main types, EHV-1 and EHV-4, cause a wide range of diseases, from respiratory infections and neurological symptoms to reproductive problems such as abortions in pregnant mares. Due to its high contagiousness, both through direct contact and contaminated objects, prevention is crucial.

Strict hygiene measures, quarantine and well thought-out stable management play a key role in minimizing infections. In addition, EHV vaccination offers protection by reducing virus excretion and reducing the severity of symptoms, even if it does not offer absolute protection against the virus.

Horse owners should consult a vet immediately at the first symptoms of equine herpes, such as fever, coughing or neurological abnormalities. Consistent preventive measures, careful monitoring and appropriate treatment can significantly reduce the risk of EHV spreading. The combination of vaccinations, hygiene and proper care ensures the best possible protection and well-being of our horses.

Herpes horse: The most important questions and answers

Equine herpesvirus (EHV) is a serious disease that can cause respiratory problems, neurological disorders and miscarriages in pregnant mares. Here you will find the most important questions & answers about symptoms, treatment, quarantine and prevention.

Is Equine Herpes Virus (EHV) deadly?

Equine herpesvirus (EHV) can be fatal in some cases, especially when the neurological form (EHM) occurs. This can lead to paralysis, impaired coordination and severe falls, which may make it necessary to euthanize the horse.

However, most infected horses show mild to moderate symptoms such as fever, respiratory disease or pneumonia. With early diagnosis and treatment, affected horses often have a good prognosis.

It is therefore crucial that horse owners and vets act quickly if an infection is suspected in order to contain the spread of the virus and avoid serious complications.

How long must a horse infected with Equine Herpes Virus (EHV) be quarantined?

The quarantine period depends on the severity of the symptoms and the recommendations of the veterinarian or the responsible health authority.

• As a rule, an infected horse is isolated to prevent virus transmission.
• Quarantine can last several weeks or even months, depending on how long the horse remains infectious.
• A horse is only considered safe when it no longer shows symptoms and there is no more virus excretion.

What should I do if my horse might have herpes?

If you suspect that your horse may be infected with EHV, you should contact a vet immediately.

Measures in case of suspicion:
✔ Isolate the horse from other horses.
✔ Strict hygiene: Wear disposable gloves, disinfect all objects.
✔ Veterinary diagnosis: Have a test carried out for the virus.
✔ Observe other horses in the stable for possible symptoms.

If it is a neurological herpes infection (EHM), the treatment options are limited. Your vet will recommend the best course of action.

Is there a vaccination requirement for Equine Herpes Virus (EHV)? 

No, the herpes vaccination requirement for competition horses was lifted on April 15, 2024.

All competition horses had to be vaccinated against EHV-1 by 2023. Following a new vote, the German Equestrian Federation (FN) decided that vaccination is recommended but no longer mandatory.

However, the Standing Veterinary Vaccination Commission (StIKo Vet) continues to regard vaccination as a "core component" of vaccination protection for horses.

Despite the abolition of compulsory vaccination, a six-monthly EHV vaccination remains mandatory:

• competition horses, as some event organizers still require vaccination.
• Horses in large stables to minimize the risk of an outbreak.
• Pregnant mares to reduce the risk of miscarriage due to EHV-1.

➡ Recommendation: Talk to your vet about the right vaccination strategy for your horse.

When does the herpes vaccination work in horses?

The herpes vaccination (EHV vaccination) takes approx. 2 weeks to build up sufficient protection.

• The vaccination stimulates the immune system to produce antibodies against the virus.
• A basic immunization consists of two vaccinations 4-8 weeks apart, followed by a six-monthly booster.

Important:

• The vaccination does not provide 100% protection against infection, but it alleviates the symptoms and reduces virus excretion.
• Additional hygiene measures and quarantine are still necessary.

How much does a herpes vaccination cost?

The cost of a herpes vaccination varies depending on the veterinary practice, region and vaccine.

💰 Price overview:
✔ Single vaccination: approx. 30-80 € per dose.
✔ Complete immunization (incl. boosters): 100-300 € per year.

⚠ Note additional costs:
In addition to the vaccination, there are other costs for the health care of the horse, including

• Regular veterinary examinations.
• Feed, bedding and medical care.
• Hygiene and protective measures to prevent infection.

➡ Tip: Find out about the total costs in advance in order to protect your horse optimally.

Is there a reporting requirement for Equine Herpes Virus (EHV)?

The obligation to report herpes in horses depends on country-specific regulations.

• In some countries, an EHV outbreak must be reported to the competent authorities.
• The regulations may vary depending on the region and the severity of the outbreak.
• Other highly contagious equine diseases are also subject to mandatory reporting in many countries.

➡ Important: Find out about the applicable regulations in your region to avoid legal consequences.

How do you protect your horse from herpes?

✅ Early diagnosis: If suspected, call the vet immediately.
✅ Quarantine & hygiene: Isolate infected horses and observe stable hygiene.
✅ Regular vaccinations: Particularly important for competition horses and pregnant mares.
✅ Monitoring in the stable: Check other horses for symptoms.

The equine herpes virus is highly contagious, but with the right measures you can minimize the risk of infection and protect your horse in the best possible way!

📌 Tip: Keep an eye on the latest developments and regulations to always ensure the best protective measures for your horse.