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Blue-green Algae Poisoning

Other Names: Cyanobacteria Toxicity

Blue-green algae (cyanobacteria) are incredibly toxic and known to cause poisoning in chickens, ducks, wildlife, dogs, cats, birds, fish, and even humans. Many people are unaware of the severity of the treat these toxins pose to animals, and are often overlooked. Most cases of blue-green algae poisoning occur during the summer, in fresh water sources when the water is warm (over 75°F (24°C)) and sunny.

Chickens are poisoned through ingestion of water containing toxic blue-green algae, which gives off the appearance of pea-green slime or paint on the surface. If ingested, the toxins can cause severe neurologic or liver damage.

Clinical Signs

Blue green color stains
Difficulty breathing
Pale face and comb (anemia)
Bloody diarrhea
Weight loss
Muscle tremors
Sudden death


  • History
  • Clinical signs
  • Physical exam
  • Laborary tests - detection of algal toxins in water samples and GI contents


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Activated charcoal2.8 g/kg administered orally as needed, to help absorb ingested toxinsK Marx



  • Regularly clean water sources, especially during hot and humid weather conditions
  • Prevent chickens' access to potentially contaminated natural or man-made stagnant or slow moving water sources (ponds, lakes, bogs, etc.)



Scientific References

Risk Factors

  • Algae growth in stagnant water sources during warm weather
  • Access to a natural water source
  • Not cleaning waterers