Equine Herpes Virus: Causes, Symptoms, Treatment, and Prevention in Horses

What is Equine Herpes Virus (EHV)/ Rhinopneumonitis?

➡️ 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."

Types of EHV: Differences between EHV-1, EHV-4 and other types

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 EHV 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.

Symptoms of an EHV infection

Equine herpes virus (EHV) can cause a variety of symptoms in horses, depending on the type of infection and the organ affected. The two main types of EHV, EHV-1 and EHV-4, often cause respiratory disease and other health problems.

Respiratory tract infections: Typical symptoms and course

‍Equine herpesvirus (EHV) infection, particularly EHV-1 or EHV-4, is one of the most common forms of herpes in horses. It can manifest itself in respiratory diseases. Typical equine herpes symptoms include fever, nasal discharge, coughing and swollen lymph nodes. The course of the disease varies, although affected horses can usually recover after a few weeks if no complications occur. The susceptibility to respiratory infections makes it all the more important to isolate affected animals immediately and provide veterinary treatment.

Neurological symptoms: paralysis and other signs

‍Inmore severe cases, the herpes virus can cause neurological symptoms in the horse in the form of EHV-1. This occurs when the virus attacks the central nervous system. Signs include paralysis, unsteady gait(ataxia), urinary and defecation disorders and even complete immobility of the hindquarters. These herpes horse symptoms can be very severe and require intensive medical care. In some cases, the disease can be fatal.

Reproductive problems: Virus-related abortions in mares

The equine herpes virus, in particular EHV-1, can cause sudden abortions in pregnant mares, often without any previous signs of disease. These abortions often occur in the last third of pregnancy and pose a serious threat to the horse population as the virus can easily be transmitted to other animals. Quarantine and isolation measures are crucial to prevent further infections and minimize the risk of another outbreak.

Transmission and infection routes of EHV

Direct transmission: Horse-to-horse contact

‍The equine herpes virus (EHV) is often transmitted through direct contact between infected and healthy horses. This occurs, for example, via nose-to-nose contact or droplet infections when horses are in close contact with each other, such as at shows or in group housing. This transmission route makes the virus particularly contagious, which is why affected animals should be isolated quickly to prevent the spread of the herpes virus in horses.

Indirect transmission through contaminated objects

‍Inaddition to direct transmission, EHV can also be spread indirectly through contaminated objects and surfaces. These include feeding bowls, water troughs, stable utensils or any other objects that have come into contact with saliva, nasal secretions or other body fluids from infected horses. Horse owners and grooms should take special hygiene measures to prevent transmission via these routes.

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 an EHV 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 tip: Dr. Christine Fuchs reports on the severe herpes outbreak in Valencia in 2021explains EHV types and gives important prevention and crisis tips. A must for horse owners and equestrians!

Recommended vaccinations against EHV: 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 tip: Hygiene in the stable: prophylaxis and emergency plan! In this video Dr. Henrike Lagershausenveterinarian from 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.

EHV vaccinations: What you need to know

What to do if a horse has herpes?

If your horse has herpes, you should do the following:

1. Contact a vet: Immediate diagnosis and treatment by a veterinarian.
2. Isolation: Separate the affected horse from other horses for at least 2-3 weeks.
3. Symptom treatment: Anti-inflammatory medication, rest and sufficient fluid intake.
4. Hygiene: Disinfect everything thoroughly, including equipment and hands after contact.
5. Stable monitoring: Check the body temperature of the other horses regularly to detect infections at an early stage.

Prevention through vaccination and hygiene measures can prevent future outbreaks.

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.

Effectiveness and protection through vaccination

‍EHV vaccination does not offer complete protection against infection, but can significantly mitigate the course of the disease. Vaccinated horses shed fewer viruses, which reduces the risk of infection for other horses. In the case of equine herpes in particular, vaccination helps to alleviate the severity of symptoms such as respiratory disease and neurological signs and to contain the spread of the virus.

Costs and legal framework

‍The cost of an EHV vaccination varies depending on the region and veterinary practice. Horse owners should expect annual vaccination costs of around 100 to 120 euros. In terms of the legal framework, there is no mandatory vaccination for all horses. However, competition horses are subject to certain regulations depending on the country and organization, which are regularly updated. It is important to find out about current regulations and develop the best vaccination strategy for your horse in consultation with your vet.

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

Is Equine Herpes Virus (EHV) deadly?

Equine herpesvirus (EHV) can be fatal in some cases in horses, particularly in the neurological form of the disease (EHM). This form can lead to severe neurological symptoms, including paralysis and incoordination, which can lead to falls and injuries. In some cases, the symptoms can be so severe that the horse has to be euthanized.

However, it is important to note that most horses that become infected with herpes develop mild to moderate symptoms, such as fever, respiratory illness, or pneumonia. Most of these cases have a good prognosis and can be successfully treated if detected early and treated appropriately.

It is therefore important that horse owners and veterinarians act quickly when herpes infection is suspected and take appropriate measures to prevent the spread of the disease and treat the symptoms to minimize the risk of serious consequences.

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

The length of quarantine for a horse infected with herpes depends on a number of factors, including the severity of the symptoms, the condition of the horse and the recommendations of the treating veterinarian or the relevant health authority.

As a rule, an infected horse is isolated and separated from other horses to prevent the spread of the disease. Quarantine can last until the horse has fully recovered and no longer shows signs of infection, or until it is no longer considered contagious . This can take several weeks or even months.

It is important to isolate the infected horse to protect other horses.

What to do if you suspect that the horse may have herpes?

If you suspect that your horse is affected by equine herpesvirus (EHV), it is advisable to consult a vet immediately. Early detection and treatment can curb the spread of the disease and contribute to the horse's recovery.

If an EHV-positive test result is available, immediate isolation of the infected animal from other horses is indicated in order to prevent further spread of the infection. Strict hygiene practices must be followed, including the use of disposable gloves when treating the infected horse and the thorough cleaning and disinfection of all objects with which the infected horse has come into contact.

If the affected horse has a neurological EHV-1 infection, treatment options may be limited and more intensive care and support may be required. Your veterinarian will provide further instructions in this case.

Monitoring other horses in the area and testing them if necessary is important to ensure that they are not also infected. Regular vaccination and careful hygiene practices are of great importance to reduce the risk of EHV infection.

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

The herpes vaccination requirement for competition horses will be lifted on April 15, 2024. Since 2023, all horses wishing to take part in competitions had to be vaccinated against EHV-1 (equine herpesvirus). The German Equestrian Federation(FN) asked the Sports Advisory Board for a new opinion and vote. The result: Vaccination is still recommended, but is no longer mandatory. 76 percent voted against compulsory herpes vaccination.

According to the Standing Veterinary Vaccination Commission (StIKo Vet), the EHV vaccination remains a "core component". Soenke Lauterbach explained on April 02, 2024 that the decision to vaccinate now lies with the horse owner again. Compulsory vaccination was introduced in 2021 after a massive outbreak of the neurological form of EHV-1 occurred at an international competition in Spain. The incident led to the temporary halt of national and international competition in Europe and had serious repercussions. A total of 19 horse deaths were recorded in connection with the outbreak.

Even before the introduction of mandatory vaccination, the discussion within the association was lively, as there are annual herpes outbreaks, which can be fatal, especially in the neurological form. During the major EHV outbreak in spring 2021, many members of the FN called for mandatory herpes vaccination. This led to the decision of the Sport Advisory Board to make the vaccination recommendation mandatory from 2023, based on the recommendations of the StIKo Vet.

For horses that regularly take part in competitions or events or live in stables with frequent horse traffic, a six-monthly EHV vaccination remains recommended. All vaccinations should be up to date before competitions and events, as some organizers require vaccinations as a condition of participation. Individual advice from a vet is advisable, as vaccination requirements may vary depending on the horse's state of health and environment.

When does the herpes vaccination work in horses?

The effect of vaccination against equine herpesvirus (EHV) in horses depends on various factors, such as the type of vaccination and the age and health of the horse.

Vaccination against EHV is usually a so-called active immunization, in which the horse receives an inactivated or weakened form of the virus. This is intended to stimulate the horse's immune system to produce antibodies against the virus in order to fight it in the event of a subsequent infection.

However, the effect of the vaccination can vary from horse to horse and also depends on the number ofvaccinations administered . However, it normally takes around 2 weeks for the horse to build up sufficient protection against EHV after vaccination.

However, it is important to note that vaccination against EHV is not 100% effective and cannot completely eliminate the risk of infection. Therefore, it is also important to take other measures to minimize the risk of infection, such as good hygiene practices and isolation of infected horses

How much does a herpes vaccination cost?

The cost of a vaccination against equine herpesvirus (EHV) can vary depending on the region, veterinary practice and type of vaccination . As a rule, a single vaccination costs between 30 and 80 euros. However, several vaccinations are usually required to achieve full protection against the virus and booster vaccinations are also necessary to maintain protection. The cost of a full vaccination, including all booster shots, can therefore be between 100 and 300 euros. It is also important to note that the current prices of a herpes vaccination can vary greatly due to the new veterinary fee schedule.

However, it is important to note that the cost of vaccination is only part of the overall cost of maintaining a horse's health and well-being. Other costs may include regular veterinary checkups, feed, bedding and any medications or treatments. It is therefore important to find out about the costs involved before acquiring a horse and to ensure that you have the financial means to care for the horse in a manner appropriate to its species and to keep it healthy.

In addition, everyone who comes into contact with horses should maintain good hand hygiene. New horses should be quarantined initially to ensure that they do not bring infections or diseases into the barn.

Regular veterinary examination of horses is also advisable to detect and treat infections and diseases at an early stage.

Effective stable hygiene requires continuous attention and effort. However, by taking the above measures, one can help ensure the health and well-being of horses and minimize the risk of infection.

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

In some countries there is an obligation to report outbreaks of Equine Herpes Virus (EHV). The exact regulations vary depending on the country and region. As a rule, animal owners or veterinarians must report outbreaks of equine herpes to the relevant authorities. In many countries, there is also an obligation to report other infectious equine diseases to ensure a rapid response from the authorities and to prevent the spread of the disease. It is important that animal owners and veterinarians are aware of the reporting requirements in their region and follow them carefully to protect the health and welfare of horses.