Equine herpesviruses EHV-1 and EHV-4: guide

Outbreak reports become outdated quickly. This page distinguishes general information about EHV-1 and EHV-4 from current official alerts.

Evergreen information and dated news

EHV-1 and EHV-4 are equine herpesviruses associated with different manifestations. An episode from 2021 should not be presented as a current emergency or automatically described as a pandemic.

Notices from authorities and equestrian organisations are authoritative for outbreaks, restrictions and movements.

Signs and isolation

Fever and respiratory, reproductive or neurological signs require veterinary contact. A suspected animal must be separated and managed using biosecurity measures defined by the professional.

Movement, shared equipment and contact between groups can encourage spread.

Prevention

Hygiene, temperature records, management of new arrivals and vaccination plans agreed with the veterinarian all contribute to prevention. No static page replaces an up-to-date animal health alert.

Sources and document updates

This information is general and does not replace diagnosis, prescription or instructions from a veterinarian. For a medicine, the summary of product characteristics or package leaflet for the specific presentation is authoritative.

• World Organisation for Animal Health — Equine viral rhinopneumonitis caused by EHV-1 (accessed 24/07/2026)
• Fédération Equestre Internationale — EHV-1 information and biosecurity (accessed 24/07/2026)

Editorial transparency: sources are provided to allow the documents to be checked. Professional review is only declared after genuine approval by a qualified, identifiable person.