Equine Herpes Virus Outbreak

As many of you will have seen in the equine press, there is currently an outbreak of Equine Herpes Virus (EHV-1) in continental Europe. The outbreak was first identified at a large show jumping competition in Valencia and has since spread to other sites in Belgium and France amongst other countries.

Many horses which contract EHV infections will have mild respiratory disease characterised by pyrexia, nasal discharge and ill thrift. A very small percentage of horses can go on to develop neurological disease (EHM), and it is this development that poses a significant risk to life. The virus currently circulating in Europe has shown the ability to cause neurological disease (EHM).

The FEI have moved to cancel all competition in mainland Europe until the 28th March to bring the outbreak under control. We expect this move will mean that many of the UK based horses currently competing in Europe will begin to return home. Returning horses should be strictly quarantined for 14 days upon their return, even if they have shown no clinical signs of disease. Herpes viruses have the ability to become latent and re-activate in times of stress such as long-distance transport. Whilst being maintained in isolation the easiest surveillance to undertake is monitoring of rectal temperatures and this should be done twice daily.

We do not advocate the practice of vaccinating in the face of an outbreak of EHM. Based on some data from a previous EHV-1 outbreak, there is evidence that recently vaccinated horses were more likely to go on to develop neurological disease. Vaccination does, however, play a major part in the control of EHV infections but should be instigated at the herd level and pre-emptive of an outbreak of disease to reduce the overall prevalence of the virus in the equine population. If you think your premises would benefit from ongoing EHV vaccination (the risk factors being similar to other respiratory viruses) then please give us a call to discuss with one of the veterinary team.