Equine Herpes Viruses including EHV-1

About Equine Herpes Virus

There are two common types of Equine Herpes Virus in horses: type 1 and type 4. Both can cause disease in horses (sometimes called Equine Rhinopneumonitis) after an incubation period of 2 to 20 days.

Clinical signs include:

• fever of 39⁰C to 40.5⁰C
• upper respiratory tract disease, coughing, nasal discharge, enlargement of glands under the jaw
• 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)

Each type also has strains which may behave slightly differently.

If you suspect Equine Herpes Virus infection

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. Unlike other viruses, such as influenza, spread is unlikely over greater distances.

The disease is spread directly from horse to horse via:

• inhalation of infected droplets
• ingestion of food contaminated by nasal discharge of infected horses
• contact with objects (such as tack, equipment, clothing) that have been contaminated.

Preventing and controlling Equine Herpes

Management practices have a significant impact on how easily the disease spreads. It is usually transmitted through close contact, sharing water, sharing tack and handlers not changing clothing and washing hands before moving between horses.

As is common with other herpes viruses, it is thought that 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:

• any new horses should be isolated first before being introduced to a group
• hygiene
• vaccination
• testing

Discuss the most appropriate with your private veterinary surgeon before you introduce any new horses.

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.

Equine Herpes Virus EHV-1

Since 1 January 2019, more than 70 cases of neurological EHV-1 have been reported in 10 countries: Belgium, Canada, Czech Republic, France, Germany, the Netherlands, Norway, Sweden, Switzerland and the USA.

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, has been reported by the FEI. 

The FEI  has announced that it has suspended international competition in the 10 countries. All of the original in-contact horses from Valencia, Vejer de la Frontera and Doha are already blocked on the FEI Database. The FEI are strongly urging all European-based FEI athletes to avoid travel with their horses during this shutdown, as travel is a clear risk factor.

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

This particular strain of EVH-1 has already caused the death of 12 horses in Europe. However, unlike other viruses such as influenza, spread over greater distances is very unlikely and effective quarantine precautions should prevent disease transmission. 

Management of showjumpers returning to UK from high risk areas of Europe