Understanding Equine Herpes Virus


It’s difficult to keep your horse from getting sick occasionally. But you can dramatically reduce the risks if you understand something about the disease in question and how to prevent it. Equine herpes virus (EHV-1) is one of those diseases, and it’s common in the horse industry.

While there are other equine viruses, herpes occurs most frequently and is often misunderstood. It shows up clinically in two major forms – the respiratory form, and the less common but much more severe neurological form. We will examine both in this article and take a holistic approach to dealing with them.

Herpes viruses have a special trait that sets them apart from many other viruses. It can hide inside the body, waiting for the immune system to become weak. Then the virus comes out and causes an illness. Stress is one factor that can suppress the immune system, so horses that travel are usually more susceptible. Any other illness and many drugs can also weaken the immune system. Pay attention to things that can stress your horse, since each animal is different.

PREVENTING EHV-1

Infectious diseases such as herpes are best dealt with by having a strong immune system that will fight the virus. However, not every horse has strong immunity, and many have quite a bit of stress in their life. Horses on a show circuit travel frequently, so are often very susceptible. They may come home from an event with an upper respiratory infection, despite efforts to protect them with vaccination.

Conventionally, we are told to vaccinate, yet horses still seem to acquire infections when competing regularly. This is because the immune system is weakened by the stress and overuse of vaccines. Vaccines on their own present a stress to the immune system. Show horses are often vaccinated on a quarterly basis, since immunity is not believed to last long. This frequent vaccination actually weakens the immune system, leaving horses more susceptible to infections.

Vaccines are not available for the neurologic form of herpes. No one really understands why the neurologic form occurs, and why its incidence is increasing. However, there is some evidence that over-vaccinating for the respiratory form of EHV-1 is not helpful and could possibly contribute to a worse neurologic case. Even the experts are noticing this, and it really supports the holistic view of improving the immune system rather than increasing vaccinations (vetmed.ucdavis.edu/ceh/ehv1_vaccination.cfm).

To help prevent EHV-1 on your farm, quarantine every new horse for at least ten to 14 days before putting him in contact with other horses. Keep your horse away from strange horses at events, and wash your hands and change your clothes if you have been near infected animals. If a horse on your farm shows signs of neurologic EHV-1, your veterinarian will help with planning a quarantine program until the danger of spread is past.

STRENGTHENING THE IMMUNE SYSTEM

The best way to prevent EHV-1 infection is to keep your horse as healthy as possible by feeding whole foods rather than processed grains, managing stress, and giving him as natural a lifestyle as possible.

Supplements that support good immune health can be used on a regular basis, or at selective times of the year when your horse is going to be under stress or exposed to outside animals, such as at a show, trail ride or clinic.

• Vitamin C is well known to help support the immune system and prevent upper respiratory infections, and it’s quite cheap to feed. Use pure vitamin C, without added filler, and feed adult horses 4 gm to 6 gm per day. This can be done all year long, or for about ten days before, during and ten days after a stressful event.

• The basis for a healthy immune system (even in the respiratory tract) is to have a healthy gut. Use pre and probiotics if there is any question about good gut health. Do not use products with preservatives and fillers as they decrease the effectiveness of the good bugs.

• Echinacea is an herb that helps support the immune system. It is safe for long-term use or during the time surrounding an event. Depending on your source for the herb, use about two to four times the human dose on the label, or use a quality brand labeled for horses.

• Omega-3 essential fatty acids (found in flax, hemp and chia seeds) are excellent for overall immunity, and are easy to feed. Many products are touted as being high in Omega-3s, but if they are processed heavily, the quantity of Omega-3 may be reduced. If feeding the above seeds, use about four ounces twice a day for an average horse. The dose can be increased very safely.

• Minerals such as zinc and selenium are used in the immune response to viral infections. Be sure your supplements contain absorbable forms of these minerals.

TREATING AN INFECTION

If your horse becomes ill with respiratory symptoms, homeopathic remedies or a few herbs will in most cases help him recover. An experienced homeopath may need to help you decide on a remedy if you see no response to the remedies you select.

If there is some nasal discharge, Pulsatilla 30C or 30X is an excellent starting point. Give six to eight tabs twice a day for two to three days. The horse should be recovering by that time. If you are able to catch his fever early, before too many other symptoms are showing up, several doses of Aconite can often prevent an infection or keep it milder than it would otherwise be.

Antibiotics may be offered by a veterinarian, but they have no effect on a viral infection, so they should not be used. The homeopathics will stimulate the immune system to do its job. A holistic veterinarian can help you get through most infections quite easily.

The neurologic form of herpes is much more serious and requires the help of a holistic veterinarian, often along with a conventional vet to give supporting treatments such as fluids. Do not try to treat this form of EHV-1 by yourself.

In conclusion, most cases of EHV-1 are mild or preventable respiratory diseases, similar to the common cold. In young horses, the disease is often just a bit of exercise for the immune system, while in older horses it may be insignificant. Horses under stress or with a weakened immune system are more likely to become sick. The neurologic form is rare and very serious. The take-home lesson is to work on the immune system of your horse.

THE TWO FACES OF EHV-1

1. Respiratory form

EHV-1 in the respiratory form is called rhinopneumonitis. It’s an upper respiratory infection that looks a lot like the common cold. Horses run a fever, usually have a runny nose, and may go off their feed. It is contagious between horses.

Equines most affected by “rhino”, as it is commonly called, are young ones whose immune systems have not been exercised by exposure to different organisms. Older or immune-compromised horses are also susceptible. Horses with a healthy immune system may get the infection, but are able to fight it off with minimal ill effects, although they become carriers.

2. Neurologic form

The neurologic form of herpes virus can easily be fatal. Horses may show a mild upper respiratory infection before they begin to display neurologic signs. In some cases, neurologic problems such as ataxia (weak and wobbly movement) are the first signs. Horses can rapidly go down and have trouble standing. If this happens, the prognosis is often poor, no matter how you treat the horse.


Dr. Joyce Harman, DVM, MRCVS, graduated in 1984 from Virginia Maryland Regional College of Veterinary Medicine. She is certified in veterinary acupuncture and chiropractic and has completed advanced training in homeopathy and herbal medicine. Her practice in Virginia uses holistic medicine to treat horses. Her publications include The Horse’s Pain-Free Back and Saddle-Fit Book – the most complete source of information about English saddles.

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