A 25-year-old unvaccinated mare was euthanised on a property near Scone last week.

According to Hunter Local Land Services, the horse developed neurological signs of the virus on Friday, June 7, three days after being confined to a yard.

AVA Equine Veterinarians Australia group president Dr Cristy Secombe admitted the incident was "extremely alarming".

"Hendra virus is a deadly virus," she said.

"For the benefit of horses and their owners, it is essential that horses located in, around or travelling to high-risk Hendra areas along the east coast, are vaccinated against Hendra virus."

From 1994, when the virus was identified, to now there have been more than 60 known Hendra incidents in Queensland and New South Wales, resulting in the death of over 100 horses.

"Every one of these horses that has died because of Hendra represents one more compelling reason for horse owners to vaccinate their horses," Dr Secombe said.

"The risk this disease poses to human health is also very real with seven confirmed cases in people leading to four deaths.

"So, it's important that the horse community remains vigilant in protecting both horses and people from Hendra."

Dr Secombe said that the vaccine, introduced in 2012, remains the most effective way to help manage the Hendra virus and is fully registered with the Australian Pesticides and Veterinary Medicines Authority.

"Vaccination of horses provides a public health and workplace health and safety benefit by reducing the risk of Hendra virus transmission to humans and other susceptible animals and helps to ensure high standards of animal health and welfare," she added.

Horse owners should contact their local veterinarian immediately for more information about Hendra virus vaccination, which is a very important part of their horse health and welfare strategy.