Abortion Alert for Horse Owners

LAST week an equine herpes virus related abortion occurred on a local property and Hunter Local Land Services has issued an alert urging horse owners to be vigilant during the breeding season.

Dr Kristi Arnot, district veterinarian for Hunter Local Land Services said horse owners need to be monitoring for the signs of equine herpes virus (EHV), which can cause abortion, respiratory disease and neurological disease in horses.

“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.”

“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.”

Once a horse is infected with the EHV-1 strain of the virus, it becomes a lifelong carrier and can shed the virus during periods of stress.

Horses which may be suspected of having the virus should be isolated and biosecurity measures put in place, which may include restricting movements of horses on and off the farm.

Vaccinations for the virus should be current and verified.

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

Please report potential cases to Hunter Local Land Services: 1300 795 299.