Victoria's chief veterinary officer, Dr Charles Milne, has warned current seasonal conditions may lead to blue-green algae thriving in farm water supplies.
Dr Milne said livestock owners needed to remain alert - blue green algae poisoning was usually seen in late summer and early autumn
It could result in the poisoning of livestock, including pets.
"As there is no specific treatment for blue-green algae poisoning, producers should check farm water supplies daily for blooms, as this remains the most effective way of preventing stock deaths," Dr Milne said.
"Blue-green algal blooms typically appear as surface scum that looks like a suspension of green paint or curdled green milk, often with an earthy smell."
However, the colour may range from pale green to dark brown.
Deaths could occur when stock drank toxins produced by the blue-green algae, often when it was concentrated on the down-wind side of a water supply and had formed a dense, surface scum.
Animals that consumed blue-green algal toxin may appear ill very rapidly, develop a staggery gait, collapse, begin to convulse and die - typically within 24 hours.
Stock that did not die immediately often suffered severe liver damage.
This might lead to the development of jaundice (the yellows) or photosensitisation over the next few days.
Dr Milne said animals that recovered from those ailments often suffered from chronic ill-thrift.
If a suspicious bloom is noticed, stock should be removed as quickly as possible, and a safe alternate water supply provided.
"Where possible producers should identify an alternative water supply, prior to their primary source of livestock drinking water being affected by a bloom," Dr Milne said.
"There may not be time to identify an alternative water source once the primary water supply is affected.
"We recommend laboratory testing of the water supply for the presence of blue-green algae, and a postmortem examination of dead or sick animals by a veterinarian."
Blue-green algae toxins might remain on dry pasture for a long-time following irrigation, often until there was a rain event or further irrigation with uncontaminated water.
It was also recommended to keep stock off pasture that has been irrigated with blue-green algae contaminated water for at least seven days after irrigation.
Dr Milne said dogs are also prone to poisoning as they tended to swim in farm water supplies and should be kept away from suspect water sources
Andrew Miller
I'm a general reporter with Stock & Land, with a special interest in irrigation issues. I completed my cadetship, with the Age, in 1980. Over my career, I've worked for ABC radio news (Mt Isa, Qld) and at provincial and suburban newspapers.
I'm a general reporter with Stock & Land, with a special interest in irrigation issues. I completed my cadetship, with the Age, in 1980. Over my career, I've worked for ABC radio news (Mt Isa, Qld) and at provincial and suburban newspapers.
