Equine Herpes Virus

Equine Herpes virus including EHV-1

Equine Herpes Virus is a contagious disease that affects horses. Although there are nine strains of the virus, Equine Herpes Virus-1 (EHV-1) and Equine Herpes Virus-4 (EHV-4) are most commonly seen. Equine herpes virus is endemic across Europe. Since 1 January 2019, more than 70 cases of neurological EHV-1 have been reported in 10 different countries: Belgium, Canada, Czech Republic, France, Germany, the Netherlands, Norway, Sweden, Switzerland and the USA. Equine herpes virus is not a notifiable disease in the Isle of Man or the UK.

An outbreak of what is thought to be a new strain of EHV-1 in competition horses, originating at a showjumping tour in Valencia, Spain, was reported to the FEI on the 20th February 2021. This particular strain of EVH-1 has caused the death of 18 horses in Europe. However, unlike other viruses such as influenza, spread over greater distances is unlikely and effective quarantine precautions should prevent disease transmission.

EHV is an endemic disease in Europe so it will continue to represent an ongoing threat after the current outbreak of EHV-1 is over. The FEI announced on the 30th March 2021 that there have been no reports of new neurological cases linked to the outbreak in Spain in the past week and the situation remains under control.

Clinical signs of Equine Herpes Virus

Clinical signs include:

  • high fever
  • upper respiratory tract disease, including nasal discharge, enlargement of glands under the jaw, coughing
  • abortion in mares (less common with EHV-4)
  • neurological signs, lack of coordination, weakness, difficulty in urinating and defecating, and inability to stand up (less common with EHV-4)

Some horses have only mild clinical signs.

If you suspect Equine Herpes Virus you should contact your private vet immediately.

How Equine Herpes Virus spreads

Equine Herpes Virus can be highly contagious, it typically spreads horse to horse over short distances of a few metres. It spreads from horse to horse via inhalation of droplets, ingestions of food contaminated by nasal discharge from an infected horse or contact with contaminated equipment.

Preventing and controlling Equine Herpes

It is usually transmitted through close contact, sharing water, sharing equipment and handlers not changing clothing or washing hands before moving between horses.

It is thought that some recovered animals may remain infected and shed the virus intermittently throughout the rest of their life.

Control and prevention methods will depend on your particular situation and may include:

  • isolating new horses before introducing them to the group
  • biosecurity and hygiene measures (especially on larger yards)
  • vaccination
  • testing

Discuss the most appropriate measures with your private veterinary surgeon.

There is more information available on the British Horse Society website. 

The FEI is also publishing regular updates on the dedicated EHV-1 hub

DEFA is continuing to review the evolving situation in Europe. Please get advice from your private veterinary surgeon before introducing any new horses (especially imported horses).