A cow has died of anthrax, a farm is in quarantine and more cases are possible.
However, Victorian authorities believe the precautions in place will prevent any outbreak of the disease.
Victoria's chief vet, Charles Milne, says the cow's death in Tatura is an isolated case on a farm with a history of anthrax, but more cases could occur.
"Farmers in the region should check their paddocks for sudden, unexplained deaths among their animals and report any cases to the 24-hour Emergency Animal Diseases Hotline ... or to their local vet," Dr Milne said on Friday.
The cow was destroyed and the property has been disinfected and quarantined, and the Department of Economic Development, Jobs, Transport and Resources is monitoring the remaining cattle for any signs of the disease.
Cattle at six neighbouring properties have been vaccinated and free vaccines are available to other farms in the area.
During the 20-day quarantine, cattle are not permitted to leave the property but milk production can continue.
Dairy Australia's manager of animal health and welfare, Robin Condron, said cases were rare but farmers needed to be vigilant.
"We haven't had a case for five years," Mr Condron told AAP on Friday.
"The vaccine is very efficient and once the immunity is established, there will be no further cases on that farm."
The risk of anthrax being transmitted from milk was negligible, he said.
Dr Milne said farmers were not required to vaccinate livestock, those in areas where the disease was prevalent, such as Tatura, were able to vaccinate stock annually for almost no cost to the farm.
"The cattle compensation fund collected from the industry will actually cover the cost of that vaccination," Dr Milne told AAP.
The anthrax bacterium has been in Australia for 150 years and occurs in the soil in parts of Victoria, occasionally causing livestock deaths.
During the last outbreak in 2007, 34 cattle died in the Tatura area and a knackery worker was treated after contracting skin anthrax.
