Agriculture Victoria is working with local veterinarians to investigate the cause of multiple sudden deaths in horses which have occurred on separate properties since Tuesday 4 July.
Victoria's Chief Veterinary Officer Dr Graeme Cooke said an investigation is underway to understand the possible cause of illness and death.
To date, there have been ten confirmed horse deaths on three separate properties. The properties are located on the Mornington Peninsula, south-east Melbourne and southwest Victoria.
"The investigation is in the early stages. It is not yet known what has caused these deaths and to date common links are not evident,"" Dr Cooke said.
All horses are believed to have died quickly with short term non-specific signs of illness.
There have been reports on social media channels of further affected properties. Agriculture Victoria is calling on any owners who have not reported deaths to contact Agriculture Victoria or their usual veterinarian to assist with investigations.
"While we do not yet have any clear indication of the cause, early testing for some known diseases in horses has been negative," Dr Cooke said.
"Comprehensive testing for a range of disease, and importantly, non-disease causes, is underway. I thank those owners and veterinarians who have been affected for their assistance in providing information to date."
Horse owners should monitor their animals and report any sudden deaths or onset of illness in their horses immediately to their local vet, Agriculture Victoria or via the emergency animal disease hotline on 1800 675 888.
"As this is early days, every report will help us understand the situation and assist our investigation into finding the cause. Early assessment and collection of a range of samples is important to this type of investigation," Dr Cooke said.
"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. Please do not share unconfirmed information online or on social media."
Multiple horse deaths on a single property are uncommon. When they occur, investigations prioritise infectious causes and ingestion of toxins, however it is not always possible to definitively identify a cause.
Horse owners are reminded to make sure their Property Identification Code (PIC) details are up to date. PICs are free and easy to get on the Agriculture Victoria website.
