Mysterious horse deaths prompt investigation in Vic [UPDATED]

UPDATED - 10:25am - 18 July 2023: The death toll of a mystery illness affecting horses in Victoria has risen to 13, with five properties now affected. There are now confirmed deaths at one property on the Mornington Peninsula, two properties near Cranbourne in south-east Melbourne, a property near Ballarat and a property near Colac.

The deaths have caused widespread concern among horse owners and trainers, and sparked a significant amount of speculation.

The Equine Veterinarians Australia president, Dr Hadley Willsallen advised: “If you are worried that your horse is not well – significantly not well – it should be looked at by a vet, and you should let the vet know your concerns as they may need to wear personal protective gear.”

Willsallen also urged people not to panic and to be conscious of the pressure that local vets were under.

ORIGINAL STORY: A cluster of mysterious horse deaths across Victoria has prompted veterinarians to conduct urgent tests to find out the cause of the disease believed to be killing them.

Distressed owners started alerting authorities after the first death on July 4 and there have been nine more fatalities since across three properties on the Mornington Peninsula, in Melbourne’s southeast and Victoria’s southwest.

All 10 horses died quickly and displaying what Agriculture Victoria described as 'short-term non-specific signs of illness'. Further reports of horse deaths have been received on its social media channels. Those deaths are yet to be confirmed and the department is urging owners and veterinarians to make contact.

The cause of the deadly disease is not yet known, but one of the concerns is how quickly the animals deteriorate.

Some of the symptoms are a loss in appetite, dull or depressed demeanour, colic, elevated temperature and diarrhoea.

Owners believe the disease is affecting younger horses and say it is not contagious.

Both the Hendra virus and anthrax have been ruled out as the cause and while a toxin in feed has been considered, there have been horses out at pasture who have been struck down.

Victoria’s chief veterinary officer, Dr Graeme Cooke, said testing for a range of disease and non-disease causes was under way.

“We know this is a difficult time for horse owners, that’s why we are working with veterinarians and a range of experts to find answers,” he said. “Please do not share unconfirmed information online or on social media.

“The investigation is in its very early stages and extensive information gathering and testing is under way to understand the possible causes of the illness and deaths.”

It is uncommon for multiple horses to die at the same time on a single property. Agriculture Victoria said it was not always possible to definitively identify a cause, although investigators prioritise infectious causes and the ingestion of toxins as possibilities.

A number of agistment properties have gone into voluntary lockdown, a precautionary measure that does not necessarily mean they have recorded sudden horse deaths.

Owners are being urged to monitor their horses and report any sudden deaths or onset of illness. Reports should be made to local vets, Agriculture Victoria or Animal Health Australia via the emergency animal disease hotline.