A HOT summer and decreasing dam water levels has prompted Agriculture Victoria to warn graziers about the dangers of blue-green algae on livestock.
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The department has warned farmers in the region to monitor dams for algae.
Chief Veterinary Officer Charles Milne said current seasonal conditions meant algae could thrive in farm water supplies.
He said livestock owners needed to remain alert, as blue-green algae could poison 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," he 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 might range from pale green to dark brown.
Dr Milne said 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 have consumed blue-green algal toxin might appear ill very rapidly, develop a staggery gait, collapse, begin to convulse and die.
Death can occur within 24 hours depending on the toxicity of the bloom and the concentration of the toxin.
Dr Milne said If a suspicious bloom was 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," he said.
"There might 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."
Dr Milne said blue-green algae toxins could remain on dry pasture for a long-time following irrigation, often until there was rain or further irrigation with uncontaminated water.
Contaminated water should not be used to irrigate vegetables and fruit.
Nor should it come into contact with plants being grown for food.
Dr Milne said producers should keep stock off pasture that had been irrigated with blue-green
algae contaminated water for at least a week after irrigation.
He said further information on blue-green contamination in irrigation water sources or livestock water supply was available at agriculture.vic.gov.au.