There are 4 strains of Equine Herpes Virus – EHV1 – 4.
- EHV1 is the most significant because it is widespread & causes abortion, stillbirths, septicaemia in newborn foals, respiratory & nervous system diseases [staggering, incoordination].
- EHV2 is common but not associated with disease.
- EHV3 causes ulcerative sores on the vulva & vagina of mares & penis of stallions, being spread during mating. Pain may prevent mating but recovery is usually complete within 2 weeks.
- EHV4 usually causes upper respiratory tract disease. On rare occasions it may be associated with abortions in individual mares but not causing outbreaks / “abortion storms”.
A vaccine is now available & is recommended for use on studs, in racing stables & for competitive horses. It will not guarantee complete protection but will greatly reduce the debilitating effects of viral respiratory disease, decrease recovery time & reduce the number of abortions in an outbreak.
The initial vaccination consists of two doses 4-6 weeks apart + a third dose in high-risk animals, followed by 6 monthly boosters. Pregnant mares should get further boosters at 5, 7, & 9 months of gestation. Previously unvaccinated mares should be treated at 4, 5, 7 & 9 months to maximise protection.
NB: The views expressed in this newsletter are by way of general discussion only & relevant veterinary advice should be sought before action is taken.