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Equine Herpes Virus -1 (EHV-1) Outbreak

EHV is a herpes virus. EHV-1 can cause four manifestations of disease in equines, including neurological form, respiratory disease, abortion and neonatal death. Wendy Conlon, Equine Specialist advises horse owners to be vigilant, outlines bio-security actions to take and provides further information

What is EHV?

EHV is a herpes virus. The current European outbreak of EHV-1 that originated in Spain at the CES Valencia Spring Tour (ESP), with horses that were in attendance at the venue from at least 1st February 2021 potentially exposed to the virus, is a form of EHV-1 that causes neurological signs, as opposed to the more common respiratory disease. EHV-1 can cause four manifestations of disease in equines, including neurological form, respiratory disease, abortion and neonatal death. EHV is not a notifiable disease. The disease can be contained by isolation and testing.

Action Protocols

In response to the current outbreak a protocol has been agreed by Horse Sport Ireland, the Department of Agriculture, Food and the Marine (DAFM), the FEI IRL National Head Veterinarian and representatives from the Irish Equine Centre which can be read here:

https://www.horsesportireland.ie/ehv-1-equine-herpes-virus-protocol-as-agreed-with-department-of-agriculture-food-and-the-marine-and-horse-sport-ireland/. There is a further link from this page to a specific ‘EHV-1 Protocol for returning FEI horses’ which is a must read for all equine owners. Minister McConalogue has also endorsed the aforementioned protocols: EHV-1 Control Advice Press Release 

The specifics of this EHV-1 Protocol were advised upon by Prof. Anne Cullinane, Head of Virology in the Irish Equine Centre. The Irish Equine Centre is an OIE (World Organisation for Animal Health) reference laboratory for EHV and provides support to the industry with their expert advice.

Further Information

Further information on EHV-1 (and other diseases) can be read in the Irish Thoroughbred Breeders Association Codes of Practice which also provides very useful advice on isolation procedures: https://itba.info/Content/2021/2/International_Codes_of_Practice_2021.pdf

It is worth noting that EHV-1 has no zoonotic impacts.

The most important part of preventing the spread of any disease is promoting good biosecurity

Biosecurity is important

The most important part of preventing the spread of any disease is promoting good biosecurity.  Awareness of, and proactivity in relation to biosecurity should be part of day to day farm management.  Covid is continuing to teach us all lessons about biosecurity in the human sense. The social distancing, hand hygiene and, for some, quarantining are all biosecurity measures which we can translate to the care of the equine.

Biosecurity means doing everything you can to reduce the chances of an infectious disease being carried onto your farm by people, animals, equipment, or vehicles. It means adopting practices as part of daily care of equines which prevent transfer of disease.

Equines are moved more often than ever before and this means they’re potentially exposed to disease more frequently as a result. Biosecurity is not something to reach for just in the instance of a disease outbreak but rather should be seen as a day to day means to prevent disease outbreak in the first place. 

Simple actions to enhance biosecurity:

There are lots of simple things which if applied on a daily basis can make a huge difference in the prevention of disease, not necessarily specific or exclusive to EHV-1, and the following are just a suggestion of some which can be applied:

  • Having an appropriate disinfection routine, with products that are virucidal, bactericidal and fungicidal for use on stables, equipment and equine transport vehicles, applied routinely between occupants/ equines.
    • Surfaces around feeders and cross ties etc. should be given special consideration due to contact with potentially infectious nasal secretions.
  • Hand hygiene between handling of individual equines is important.
  • Separate persons should manage separate groups of equines if possible, particularly on larger establishments. Where this is not possible manage more vulnerable groups first i.e. pregnant mares and youngstock.
  • Provide separate equipment for each equine or group of equines.
  • Use disposable coveralls and gloves, in particular when handling pregnant mares at foaling time, disposed of safely afterwards.
  • Equines returning home from a temporary departure from the premises, and any new equines on the premises should be isolated for two weeks following return to allow early detection of disease and have their temperature monitored regularly.
  • Daily temperature monitoring of all resident equines on a premises is a very useful practice, particularly with stabled equines with which it is more practical to achieve.
  • Segregate different categories of equines on a facility by use and age. For example competition equines should be segregated from broodmares and foals.
  • When filling water buckets don’t submerge hoses in a bucket when filling.
  • Clean stables regularly and store waste away from the stables.Don’t use equipment for cleaning stables (i.e. wheelbarrows) for feeding purposes (moving hay or hard feed) or to move clean bedding.
  • Stabling which prevents equine to equine contact over walls; through walls; or into the aisle way limits disease transmission
  • Equipment (feed buckets, water buckets, halters, pitchfork, wheelbarrow, etc.) should be clearly identified as belonging to an individual equine or group of equines and used only for that equine or group. (relative to the size of enterprise)
  • Cloth items (saddle cloths, towels, bandages, halter fleeces etc.) should be laundered and thoroughly dried between each use. (Disinfectant may be added to rinse water, with an additional rinse cycle to remove disinfectant residue.)
  • Equipment that cannot be effectively disinfected (sponges etc.) should not be shared between equines.
  • Multiple dose medications (oral pastes/ophthalmic ointments etc.) should be labelled for use by a specific equine and not shared.
  • Ointments/topical medications should be removed from larger tubs and distributed into smaller containers for use on individual equines
  • More specific advice relating to the management of equines in isolation is included in the ITBA Codes of Conduct and ‘EHV-1 Protocol for returning FEI horses’ referenced above.


In relation to the current situation with EHV, it is important to remain vigilant and careful, particularly if new equines are entering the farm; or equines are returning to the farm. Isolation and quarantine of such animals is imperative regardless of where they have travelled from. Contact the local veterinarian if any causes for concern arise.

See more Teagasc Equine information of interest here