Equine herpes – risks, prevention and treatment

Equine herpes (also known as the ‘equine herpes virus’) is a highly contagious virus that infects almost every horse. The virus is triggered by psychological stress or other illnesses, among other things. The symptoms can vary in severity depending on the horse’s age and condition. We will explain the risks of the virus, how to prevent an outbreak, and which treatment approaches there are below.

Most horses become infected with the equine herpes virus when they are foals. While the infection persists throughout a horse’s life, it does not necessarily reactivate or exhibit symptoms.

Transmission is more likely during the wet and cold season, since such climatic conditions are more favourable for the virus. The pathogen can survive on objects for up to three months.

Equine herpes is what is known as a ‘droplet infection’ transmitted from infected horses to healthy ones. The possibility of indirect infection through humans, feeding sites or other contact objects cannot be excluded either.

One cause of herpes outbreaks in horses is stress. Since horses are flight animals, they avoid danger and stress through their flight instinct. But if their ‘escape’ is prevented, their stress level increases. Transportation, tournaments or loud, unfamiliar noises in particular cause stress.

There are five known types of equine herpes viruses worldwide. In the following list of symptoms of equine herpes virus (‘EHV’ for short), we are referring to types EHV-1 and EHV-4, which are the most common. In sick animals, the herpes virus has the following effects:

• Febrile respiratory diseases (EHV-1/4)
• Loss of appetite / reluctance to eat (EHV-1/4)
• Elevated body temperature (exceeding 39°C) (EHV-1/4)
• Watery nasal discharge (EHV-1/4)
• Watery eye discharge (EHV-1/4)
• Foaling / miscarriage in pregnant mares (EHV-1/4)
• Severe course with bacterial infection (EHV-1/4)
• Damage to the nervous system (EHV-1)
• Loss of coordination and paralysis (EHV-1)

Both variants attack the upper respiratory tract. The EHV-1 variant can also lead to the dreaded neurological form, causing a drastic course of the disease. If you notice these or similar symptoms in your beloved horse, contact a vet immediately.

Even if you only suspect that your horse has herpes, you must isolate it immediately and avoid contact with other horses. Contact a horse clinic or a vet. Samples are taken for diagnosis using a nasal or uterine swab.

The collected samples are then analysed using PCR. In the neurological progressive form of the disease (EHV-1), additional measures are necessary for diagnosis. Further examinations and treatments take place in a quarantine station to prevent transmission.

The prospects of recovery from the EHV-4 variant are very good. No late complications are to be expected, and mares can also become pregnant and give birth again after suffering miscarriages. Some courses are even asymptomatic. Unfortunately, the prognosis for the EHV-1 variant is worse. Under certain circumstances, it can even prove fatal or lead to serious late complications. If the nervous system does not fully recover, paralysis and failure can occur, so in the worst-case scenario the vet will have to put the horse down.

Equine herpes cannot be treated directly. It is only possible to reduce the symptoms to support the immune system. There are also measures and remedies to help the sick horse on its way to its recovery and to spare it unnecessary suffering.

If the disease is diagnosed, the symptoms can be treated with the following remedies:

• Anti-inflammatory medication
• Medication to support the circulation and immune system
• Vitamin B as a supplement to medication
• Antibiotics in case of bacterial infection

In any case, talk to your vet before administering medication to the sick horse. Preparations should only be discussed and administered with knowledgeable experts.

If your horse is sick, you must take measures immediately to protect the rest of the herd and prevent a mass outbreak:

• Apply strict quarantine rules for all horses
• Do not permit horses to leave the farm
• Do not allow other people’s horses to enter the grounds
• Take all the horses’ temperature twice a day
• Avoid direct contact
• Quarantine the sick horses
• Disinfect utensils, clothes and shoes
• Disinfect before and after contact with the sick horse
• Have people coming into contact with sick horses wear sterile protective clothing and gloves
• Disinfect the stable once the symptoms have disappeared

Also, do not underestimate emotional support. Being sick with equine herpes is stressful for your beloved horse. Social isolation from its herd is problematic for this sensitive animal. If possible, try to spend time with your horse anyway. But do bear in mind that you can be a carrier of the virus too and infect other horses.

Getting horses vaccinated is a sensible move, because they can come into contact with the virus even as foals. The Swiss Veterinary Commission (VETKO) recommends vaccinating horses from the age of 6 months, followed by the second vaccination at an interval of 4 to 6 weeks and the third vaccination at an interval of 4 to 6 months. After that, the animal is vaccinated for 6 months.

Regular vaccination at 6 month intervals is recommended as a booster. Vaccinated horses have better protection against the herpes virus. In pregnant mares, booster vaccination is recommended in the fifth and seventh months of pregnancy. Vaccination in the ninth month of pregnancy is also advisable to protect the unborn foals and prevent miscarriage.

In most cases, equine herpes is harmless and soon forgotten. The prospects of happier moments often help with getting through what is indeed a difficult time. However, it is always advisable to take good precautions against the worst happening, because every moment spent with your beloved horse is precious.

A cremation plan for horses allows you to make all the financial and organisational preparations to say an appropriate and dignified final farewell to your horse at an early stage. You make all the important decisions at a time when you have both the peace and the strength to do so. Afterwards, you can enjoy spending time together without a care in the world and, if the worst does happen, you can confidently turn to the team at ROSENGARTEN Animal Crematorium to make sure your final farewell to your beloved horse is a dignified one.

We have once again provided questions and answers below, this time dealing with everything you need to know about equine herpes.

How is equine herpes transmitted?
Equine herpes is transmitted by droplets from infected animals. But the pathogen can also survive on everyday objects and people.

Can equine herpes be transmitted to humans?
Humans cannot contract equine herpes.

Can horses die from the herpes virus?
The neurological process of the herpes virus EHV-1 is particularly dangerous for horses and can, in the worst-case scenario, prove fatal.

How can you tell if the horse is healthy again?
You can tell that a horse has recovered by the fact that the symptoms have completely disappeared, and it is enjoying life again and its appetite has returned. A vet can tell you when they are certain the virus is finally no longer being excreted.