HERPES VIRUS ABORTION (EHV)

The Animal Health Trust in Newmarket has isolated 10 herpes virus related abortions during the last 9 months of 2001. EHV- 4 was diagnosed in 2 cases and EHV-1 in the remaining mares.
There were also three herpes virus neonatal deaths reported.

Equine Herpes Virus (EHV) is associated with a variety of clinical findings including respiratory disease, abortions, neonatal mortality and neurological disorders. The disease has a complex epidemiology and has the complication that clinical, subclinical and latent carriers all excrete the virus.

The disease is commonly associated with the usual management activities that bring together in close proximity large numbers of horses which produce stress e.g. sales conditions, transport, weaning, training.

In mares, abortions due to EHV infection occurs in the last trimester but the time interval between infection and abortion varies from weeks to months.

We recommended that all mares should be vaccinated with Duvaxyn EHV 1-4 (which protects against strain 1 & 4) at 5, 7 and 9 months of pregnancy. It is also recommended to vaccinate all animals on the premises.

Non pregnant animals should be vaccinated from 5 months of age with two vaccinations 4-6 weeks apart followed by booster vaccinations every 6 months.

In the event of increased infection risk e.g. disease outbreak foals can be vaccinated earlier from 3 months of age.

EQUINE INFLUENZA

There still seems to be much confusion over the rules and regulations with regard to vaccinations against flu.

The rules of racing require that for horses born since 1980 (which by now would include most if not all competition horses).

Two vaccinations are given 21-92 days apart followed by a third vaccination 150-215 days later. Annual boosters are then given thereafter.

Horses are not allowed to compete within 7 days of receiving the vaccination. They are however allowed to compete after the initial two vaccinations as long as the third vaccination has not expired.

Most competition horses e.g. eventing, show-jumping follow these rules. It is always recommended that checks are made to ensure that the vaccination policy complies with individual ruling.

We always recommended that tetanus cover should always be included with the influenza vaccination programme.