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Sudden Death Syndrome

Flip-over Disease, Acute Heart Failure

Sudden Death Syndrome Overview

Sudden death syndrome (SDS) is the name given for the unknown cause of chickens suddenly developing short, wing-beating convulsions that result in them 'flipping over' (hence why the condition was originally termed, 'flip-over disease'). SDS occurs in young, healthy, fast-growing, commercial broilers. Just prior to death, chickens will suddenly gasp, extend their necks, squawk, and/or flap their wings, causing them to flip over on their backs. The cause of SDS is thought to be linked to cardiac arrhythmias and/or possibly associated with a metabolic disease resulting from high levels of carbohydrate consumption.

Clinical Signs

Extension of necks
Flapping wings
Flipping over backwards
Found dead on their backs, sides or breasts


  • History
  • Clinical signs
  • Physical exam
  • Necropsy


No treatment is available as it is such a sudden onset and rapid death.


  • Reduce growth rate of chickens, especially the first three weeks upon hatching.
  • Reduction of light exposure
  • Switching to a low-energy diet
  • Minimizing stressful triggers


It is fatal.

Scientific References

Age Range

Peak mortality occurs when chicks are between 2-4 weeks of age.

Risk Factors

  • Stress