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Avian Amyloidosis

Amyloidosis is a complex and poorly understood disease, caused by extracellular amyloid deposits that often lead to organ dysfunction and death in humans and animals. Amyloids are insoluble proteins that form abnormal fibers (amyloid fibrils) in various organs within the chicken's body. The presence of amyloid causes damage or altered function of the organs as it accumulates in tissue cells. The presentation of amyloidosis is broad and depends on the specific organ(s) affected and the amount of amyloid accumulation.

In humans, amyloid deposits from different, misfolded protein precursors have been associated with Alzheimer's disease, type II diabetes mellitus, multiple myeloma, familiar amyloid polyneuropathy, senile systemic amyloidosis, and inflammation-associated amyloidosis. Inflammation-associated amyloidosis, also referred to as amyloid A (AA), acquired, secondary, or reactive amyloidosis occurs systemically in susceptible chickens when excessive amounts of serum AA (SAA) protein are produced, primarily by the liver, resulting from chronic inflammation. Pekin ducks and brown laying hens have both been used as important research models of AA amyloidosis due to their predisposition. In chickens, AA amyloidosis is observed as amyloid arthropathy.

Outbreaks of fatal AA amyloidosis has been documented in flocks of growing chickens within 3 weeks of receiving multiple co-administered vaccines. Systemic amyloidosis outbreaks have occurred in layer flocks that received multiple vaccinations with oil-emulsified bacterins.

Clinical Signs

Leg and joint swelling
Unexplained weight loss
Muscular weakness
Sudden death


  • History
  • Clinical signs
  • Immunohistochemistry
  • Biopsy
  • Necropsy


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.


  • Prevention of chronic inflammatory conditions such as bumblefoot, gout, arthritis, aspergillosis, etc.
  • Do not administer multiple vaccines in one setting to chickens.

Scientific References

Good Overviews

Risk Factors

  • History of chronic inflammation or trauma
  • Existing tumor
  • Overcrowding
  • Recently administered multiple vaccinations.