Equine Herpesvirus

There are five types of Equine Herpesvirus that affect horses and donkeys in Australia. Equine Herpesvirus 1 (EHV-1) and Equine Herpesvirus 4 (EHV-4) are the most common and cause the greatest health risks for horses. EHV-1 is the most detrimental type of the virus as it can cause abortion outbreaks. It is responsible for respiratory and neurological diseases as well as abortion in mares. EHV-4 is also known as equine rhinopneumonitis and most commonly causes respiratory illnesses in young horses and is occasionally responsible for abortion in mares and neurological diseases.

Equine Herpesvirus is highly contagious and spread through contact with infected nasal discharge, either via horse to horse contact or contact with contaminated equipment. Transmission also occurs through contact with an aborted foetus, placenta or placental fluids. It can also be transmitted on the air for short distances. Once infected with EHV the virus is latent for life in the horse and may reactivate when they become stressed. A once infected horse becomes a carrier and can pass it onto other horses without displaying any symptoms themselves.

Signs of EHV-1 and EHV-4 include; fever, depression, loss of appetite, coughing, nasal discharge and abortion. Abortion in mares is more commonly caused by EHV-1 and usually occurs during the later stages of pregnancy, between 7-11 months of gestation.

There are vaccinations available for Equine Herpesvirus in Australia. Duvaxyn EHV 1,4 Vaccine is available through veterinarians for vaccination against EHV-1 and EHV-4. The first vaccination can be given from 5 months of age, followed by a second injection 4-6 weeks later. The horse then requires a booster vaccination every 6 months. Pregnant mares should be vaccinated at 5, 7 and 9 months of gestation to reduce the chance of EHV related abortions.

For more information on Equine Herpesvirus or the Duvaxyn EHV 1, 4 Vaccine please contact your veterinarian. If a mare does abort a foal please contact a veterinarian as if it is caused by EHV in some states it is a notifiable disease and needs to be reported to Biosecurity.