December 1st, 2022Warning to look out for blue-green algae in farm water supplies

Recent flooding events combined with warmer weather conditions has produced favourable
conditions for blue-green algae to thrive in farm water supplies and standing flood water.
Senior Veterinary Officer Dianne Phillips said livestock owners need to remain alert – ingestion of
blue-green algae can result in the poisoning of livestock
“As there is no specific treatment for blue-green algae poisoning, producers should check standing
bodies of water and farm water supplies daily for blooms, as this remains the most effective way of
preventing stock deaths.
“Blue-green algal blooms typically appear as surface scum that looks like a suspension of green
paint, often with an earthy smell. However, the colour may range from pale green to dark brown,”
Dr Phillips said.
Deaths can occur when stock drink toxins produced by the blue-green algae, often when it is
concentrated on the down-wind side of a water supply and has formed a dense, surface scum.
Animals that have consumed blue-green algal toxin may appear ill very rapidly, develop a
staggering gait, collapse, begin to convulse and die – typically within 24 hours – depending on the
toxicity of the bloom and the concentration of the toxin.
Those that don’t die immediately, often suffer from severe liver damage. This may lead to the
development of jaundice (the yellows) or photosensitisation over the next few days. Livestock that
recover from these ailments often suffer from chronic ill-thrift.
If a suspicious bloom is noticed, the water supply should be isolated 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. There may not be time to identify an
alternative water source once the primary water supply is affected,” Dr Phillips said.
“We recommend laboratory testing of the water supply for the presence of blue-green algae and a
post-mortem or examination of dead or sick animals by a veterinarian.”
Contaminated water should not be used to irrigate vegetables and fruit or come in contact with
plants being grown for food, particularly fruit and vegetables that are mostly eaten raw such as
apples, grapes, tomatoes, strawberries, cabbages and other salad greens.
Dr Phillips said dogs are also prone to poisoning as they can swim in farm water supplies and
should be kept away from suspect water sources