09/11/2026
VACCINATING FOR EQUINE HERPES VIRUS (EHV)
What is EHV?
EHV refers to a group of 5 herpes viruses that can cause respiratory illness, abortion + abortions storms in pregnant mares, and neurological diseases. The most clinically important of these viruses are EHV-1 and EHV-4.
If your mare is in foal, now is a good time to think about protecting her against Equine Herpesvirus (EHV). EHV-1 is an important cause of infectious abortion in horses. Infection during pregnancy can result in abortion, stillbirth, or the birth of a weak foal. Unfortunately, mares can sometimes carry and spread the virus without showing any obvious signs of illness.
Why vaccinate your pregnant mare?
Vaccination against EHV-1 helps to reduce the risk of abortion associated with infection. It is an important part of managing the health of broodmares.
When should my mare be vaccinated?
The recommended vaccination schedule for pregnant mares is three additional EHV vaccinations during pregnancy:
· 5 months pregnant – first gestational booster.
· 7 months pregnant – second gestational booster.
· 9 months pregnant – third gestational booster.
These vaccinations are given in addition to the mare's routine EHV vaccination programme, including six-monthly boosters where appropriate. If your mare has never been vaccinated against EHV, or her vaccination history is incomplete, contact us for further information.
Can vaccination completely prevent EHV?
Unfortunately, no. Vaccination helps reduce the risk of EHV-associated abortion but does not provide complete protection against infection. Good biosecurity is equally important.
We recommend:
· Quarantining new arrivals before introducing them to the yard.
· Avoiding sharing buckets, equipment and tack between horses.
· Monitoring pregnant mares for signs of illness, particularly raised temperatures.
· Isolating any horse showing signs of respiratory disease or illness and contacting your vet.
When planning for foaling, making sure your mare is up to date with her vaccinations is an important part of preparing for a healthy pregnancy and future foal.
If your mare is in foal and you would like to discuss her EHV vaccination status, get in touch with the practice. Our vets are happy to help you plan the most appropriate vaccination schedule for your mare.