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Pyrrolizidine Alkaloid Toxicity

Pyrrolizidine alkaloid (PA) toxicity occurs in chickens as a result of eating plants containing pyrrolizidine alkaloids. It can be an acute poisoning if large enough quantities are eaten, however it is most often the result of a chronic poisoning, where clinical signs may take weeks to months following consumption of a sufficient quantity of the toxic plant. Toxicity is cumulative, over the course of a chicken's lifetime.

PAs belong to a class of phytotoxins which are present in more than 6000 plant species. Some of the most commonly known causes of poisoning cases in chickens and other farm animals include:
Pyrrolizidine alkaloid containing plants

PA toxicity causes liver disease. Chickens with liver disease may not initially show any clinical signs, or the symptoms can appear very vague and often are confused or mistaken for other diseases. Toxicity occurs in chickens of all ages and breeds, but not all members of the flock will develop signs of liver damage.

Clinical Signs

Loss of appetite
Neurologic behavior abnormalities
Excessive drinking


  • History
  • Clinical signs
  • Physical exam
  • Low plasma or serum zinc levels

Reported Cases

  • Case 1: Pyrrolizidine alkaloid poisoning in a Chickens and ducks The disease produced by feeding chickens and ducks a commercial poultry feed containing heliotrine and lasiocarpine, pyrrolizidine alkaloids of Heliotropium europaeum, is described. Poor condition, ascites and degenerative lesions in the liver were the major findings. Similar lesions occurred in chickens fed a diet containing H. europaeum. The source of the alkaloids in commercial poultry feed was probably the seeds of H. europaeum harvested with wheat. Ref


Supportive care: Isolate 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.:



Learn how to identify what plants contain PAs, and regularly inspect the premises for their presence



Scientific References

Risk Factors

  • Overgrowth of PA-containing plants in fields where chickens are kept, as they are often considered to be common weeds in many parts of the World.
  • If feeding your flock dried herbs, ensure they are purchased from reputable companies which practice quality control testing on their products, especially when involving comfrey.