Equine Herpes Virus (EHV) – Abortion alert for Hunter horse owners

Hunter Local Land Services is urging horse owners to be aware of the risks of Equine Herpes Virus (EHV).

An EHV-1 abortion occurred on a local property, and during the 2018 breeding season, a number of EHV-1 abortions were reported to Hunter Local Land Services.

There are a number of different Equine herpes viruses that may infect horses.

Equine Herpes Virus 1 (EHV-1) causes respiratory disease, abortion and neurological disease in horses and is a significant problem in horse industries around the world.

Once infected with EHV-1, a horse becomes a lifelong carrier of the virus which may then reactivate and be shed during periods of stress.

District Vet Dr Kristi Arnot said it is a crucial time for horse owners to be monitoring for signs of Equine Herpes Virus.

“Most mares are now due or will soon be due for their five month vaccine, the first in the series of three that they need,” said Dr Arnot.

“Horse owners need to be aware of so-called ‘abortion-storms’ where one EHV related abortion in a single mare may be followed a few weeks later by abortions in multiple mares on the farm if strict biosecurity practices are not followed.

“For more than a decade now this disease has been managed in Australia by a combination of vaccination programs and management practices in an attempt to reduce the risk of abortion storms.”

Most horse studs will have an EHV policy in place for visiting mares.

It is recommended that vaccination status be checked and preferably verified.

Treating veterinarians should be able to state when vaccination has occurred, as vaccination is available only via veterinarians.

Some factors that have been associated with EHV-1 abortion include:

  • Stress – including transporting mares late in gestation
  • Mixing groups of pregnant mares late in gestation
  • Co-mingling pregnant mares with barren mares and young horses (weanlings/yearlings etc)
  • Failing to follow strict biosecurity and hygiene protocols following an initial EHV-1 abortion case
  • Mares purchased pregnant and unvaccinated

Susceptible mares may inhale or ingest EHV-1 from the following sources:

  • Aerosols, fluids or foetal matter from aborted mares
  • Young horses with ‘colds’
  • Clinically healthy carrier horses
  • Pasture, feed bins, water troughs, halters, rugs, bedding, floats and staff clothing that have been in contact with affected horses

“After an abortion, mares clear the virus from their reproductive tracts in a few days, but can shed virus from their respiratory tract for up to 14 days,” said Dr Arnot.

“The virus may remain infective in the environment and on horse hair for up to six weeks in cool, moist conditions.

“EHV is a notifiable disease in NSW and must be reported to the Department of Primary Industries, with aborted foetuses to be sent for laboratory diagnosis.”

It is important the mare that has aborted is isolated immediately, until the diagnosis is confirmed.

During an outbreak, the movement of horses on and off your farm may be restricted.

This will include the movement of horses to other farms to be covered by stallions or for foaling and the movement of horses for sales.

Talk to your veterinarian about how best to protect your horses.

If you notice anything unusual or are aware of a plant or animal disease threat, please contact Hunter Local Land Services on 1300 795 299.

Source: Hunter Local Land Services

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