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Rhino virus

Rhino virus

Rhinopneumonia (EHV) is a herpes virus infection caused by two different herpes viruses (EHV1 and EHV4) and has three manifestations:

  • cold form
  • abortion form
  • neurological form

The cold form is very common in young horses in particular and is mainly caused by EHV4. The horses do not always have clinical signs, but the following symptoms may occur: fever, nasal discharge, respiratory symptoms, loss of appetite and / or swollen legs. Very rarely, infection with EHV4 may cause abortion and / or neurological signs.

EHV1 is a more dangerous variant. This can, among other things, cause respiratory symptoms, but is also often the cause of an abortion or very weak foals that often die. This variant can also cause neurological symptoms. This usually starts with a floppy tail and ataxia. More serious paralysis symptoms may also occur. Usually only the back legs are affected, but in the most severe cases the front legs can also be involved.

Fortunately, the neurological form occurs only occasionally. All horses in the Netherlands regularly come into contact with these viruses (almost all horses with EHV4 and 20-40% of horses with EHV1). Unfortunately, it is not known why an equestrian centre is sometimes affected by abortions or paralysis problems.


The spread of the rhinopneumonia virus mainly takes place through direct contact between horses or by housing together in one room. In principle, the virus can also be transmitted by humans through clothing and hands when it passes from one horse to another. By taking a good shower and clean clothes and shoes, this form of transmission can be ruled out. Passing horses on the street or in the forest is not a possible source of contamination when direct contact is avoided.


To confirm an EHV infection, a nasal swab and possibly a blood test must be performed. In the event of an abortion, the rejected fetus and placenta should be examined.


Regular therapy is not possible. We often prescribe supportive medication that has an effect on the immune system. If you would like more information about this, please contact one of our veterinarians.


A vaccine is available, but it does not protect against all variants of the virus. In the case of the cold, vaccination can reduce the respiratory symptoms. Vaccinating a pregnant mare at a previously infected farm can be useful if the mare is vaccinated four times a year. Unfortunately, the efficacy of a Rhino vaccination to prevent abortion is uncertain. The vaccine does not protect against the neurological variant.

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