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

What is Equine Herpes Virus (EHV)/ Rhinopneumonitis?

Herpes viruses are a group of viruses that can cause various types of diseases in humans and animals. Equine herpes virus (EHV), also known as rhinopneumonitis, is a group of herpes viruses that can infect horses. EHV-1 and EHV-4 are the most common types of EHV that can cause problems for horses.

EHV-1 can cause various diseases in horses, including respiratory infections, abortion in pregnant mares, paralysis and neurological diseases. EHV-4 is mainly responsible for respiratory diseases.

Equine herpes virus is highly contagious and is spread through direct contact between infected and uninfected horses. It can also be transmitted through contaminated objects such as water troughs, feed bowls and equipment. To minimize the spread of Equine Herpes Virus, it is important to follow good hygiene practices at home and at shows.

There is no specific treatment for EHV, but veterinarians can treat symptoms and support the patient until the virus is overcome. Vaccines are available to protect horses from some types of Equine Herpes Virus, but they are not 100% effective. To minimize the risk of EHV infection, it is important to follow regular vaccination and good stable hygiene.

What are the symptoms of Equine Herpes Virus?

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.

EHV-1 can lead to these symptoms in horses:

• Fever
• reduced appetite
• Breathing difficulties
• Cough
• Nasal discharge
• swollen lymph nodes
• abortions in pregnant mares
• Birth of foals with neurological deficits
• Neurological EHV-1 infections can lead to serious coordination problems, weakness, paralysis and even death.

EHV-4 can lead to these symptoms in horses:

• Mild respiratory infections with symptoms such as nasal discharge, cough and fever
• serious illnesses such as pneumonia, respiratory diseases, cough and fever

It is important to note that some infected horses may show no symptoms but can still transmit the virus to other horses.

If you notice signs and symptoms of EHV infection in your horse, you should consult a vet immediately. Treatment for Equine Herpes Virus focuses on relieving the symptoms and helping the horse to recover. There is no specific treatment for EHV, but regular vaccinations and good hygiene management can help minimize the risk of infection.

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.

How is Equine Herpes Virus (EHV) transmitted?

Equine herpesvirus (EHV) is transmitted from horse to horse through direct contact . Infection can occur through the ingestion of secretions from the nasal and eye areas of an infected horse, or through contact with infected urine or feces. Objects such as feeding troughs, drinking buckets, brushes or saddlery can also transmit the virus if they are used by an infected horse and are not thoroughly cleaned and disinfected afterwards.

It is important to note that an infected mare can also transmit the virus to her foal, either before or during birth or through the milk after birth. EHV can also be transmitted through the air, especially when infected horses cough or sneeze.

It is important to take appropriate precautions to prevent the spread of the virus. These include, for example, testing new horses for EHV before integrating them into a herd, isolating infected horses, and following thorough hygiene measures, especially when using shared feed, water, and equipment.

How to prevent Equine Herpes Virus (EHV) in horses?

There are several steps horse owners can take to minimize the risk of equine herpesvirus (EHV) infection in their horses:

The herpes (EHV) vaccination

Vaccination against EHV is available and should be administered regularly to strengthen the horse's immune system and protect it from infection.

When do you have to vaccinate a horse against Equine Herpes Virus (EHV)?

Vaccination against equine herpesvirus (EHV) should be carried out regularly to protect the horse from infection. The exact vaccination recommendation depends on various factors, such as the age of the horse, its state of health and its risk of being exposed to the virus.

In general, it is recommended to vaccinate foals against EHV at the age of 4 to 6 months. The initial vaccination should be refreshed by a second vaccination within 4 to 6 weeks of the first vaccination. It is also recommended that a booster vaccination be given annually.

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

The herpes vaccination requirement for competition horses will be lifted in 2024. Since 2023, all horses that wanted to take part in a tournament had to be vaccinated against EHV-1. The German Equestrian Federation (FN) once again asked the Sports Advisory Board for an opinion and a new vote. The result was that the vaccination is still recommended, but the obligation to vaccinate will be lifted from April 15, 2024. 76 percent voted against the herpes vaccination requirement.

According to the Standing Veterinary Vaccination Commission, vaccination against herpes is a "core component". "Therefore, the recommendation for vaccination remains in place," confirmed Soenke Lauterbach on April 2, 2024, adding that the decision is now once again up to the horse owner.

When the Sports Advisory Council made the decision to make vaccination compulsory in the summer of 2021, the circumstances were very different. In 2021, there was a massive outbreak of the neurological form of EHV-1 at an international tournament in Spain. As a result, international and national tournament sport in Europe was suspended for several weeks. The impact of the tournament stoppage was considerable. In connection with the outbreak, 19 horse deaths were recorded. A herpes vaccination requirement has been discussed within the association for several years. This is because there are herpes outbreaks every year, which can often be fatal for affected horses, especially in the neurological form. In addition, during the outbreak in spring 2021, the FN received many requests for compulsory herpes vaccination from its members. For these reasons, the Sport Advisory Board considered the introduction of compulsory herpes vaccination and ultimately turned the recommendation into a requirement from 2023. At that time, the Sport Advisory Board followed the recommendations of the Standing Veterinary Vaccination Commission.

For horses that regularly participate in shows or other events, or are housed in a barn with frequent horse traffic, bi-annual vaccination may be recommended. It is also important to make sure all vaccinations are up to date before a horse travels to a show or other event, as some event organizers may require vaccinations as a condition of participation.

It is best to speak with a veterinarian to get the exact vaccination recommendation for a specific horse, as requirements may vary based on individual health and environmental conditions.

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.

Hygiene in the stable

Good hygiene practices are essential to prevent the spread of the virus. Good stable hygiene is a crucial factor for the health and well-being of horses. To ensure effective stable hygiene, stable owners and staff should take certain measures.

Regular cleaning of the stable is one of the most important measures. It is advisable to clean the hutch daily and remove droppings, urine, straw or hay as well as dirt from the feed troughs and drinking troughs. Cobwebs and dust should also be removed.

Disinfection of the stable is another important aspect of stable hygiene. Special disinfectants suitable for horses should be used for this purpose. Complete drying of the stable should be ensured before the horse enters.

It is advisable to separate infected horses from healthy horses to prevent the spread of infection. Clean and dry bedding also helps to prevent infections.

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.

Isolation and quarantine in case of suspected herpes 

Infected horses should be isolated from other horses to prevent spread of the virus. Separate stabling and equipment should be used for infected horses.

Testing for Equine Herpes Virus

New horses should be tested for Equine Herpes Virus before being integrated into a herd to ensure that they are not infected.

Observation of conspicuous symptoms of equine herpes virus

Horse owners should monitor their horses regularly to detect signs of EHV infection early and act quickly.

By taking these precautions, horse owners can reduce the risk of EHV infection in their horses while helping to minimize the overall spread of the virus in equine populations.

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.