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Avian Amyloidosis, AA‐amyloidosis
Avian amyloidosis is a well-recognized pathological disorder which is a common cause of death in birds, especially domestic ducks. It is a fatal progressive condition in which an abnormal protein (amyloid) builds up within the bird's tissues and organs, leading to organ failure. Although there are several types of amyloidosis that occur in humans, ducks are most frequently affected by the inflammation-associated form---also known as AA‐amyloidosis or systemic amyloidosis.
Avian amyloidosis is often found to occur as a secondary result of several diseases, especially chronic infections. Any ducks with existing chronic inflammations (aka bumblefoot, gout, frostbite, and avian tuberculosis) or tumors are more at risk. It has been found that prolonged inflammation causes a significant increase in the serum levels of the hepatic acute phase reactant serum amyloid A (SAA), the precursor protein of amyloid protein A (AA).
Increased incidences of amyloidosis have been shown to occur in ducks kept in overcrowded, stressful living conditions. In one study, up to 71% of ducks developed amyloidosis who were kept in overcrowded living conditions.
How is Amyloidosis Diagnosed?
Since clinical signs of amyloidosis are non‐specific, diagnosis requires histopathology following biopsy or necropsy to obtain a definite diagnosis.
Case 1: Amyloidosis and Gout in a Flamingo On presentation, a flamingo was weak and thin. Supportive care was given, but bird was found dead two days later. The plantar aspects of both feet have thickened/calloused 1-1.5 cm diameter lesions with a small central crater over the proximal joints of digits one, two, and three. Associated joints contain cloudy, viscous fluid. Ref
Case 2: Hepatic myelolipoma with systemic amyloidosis in a Swan An adult swan goose kept in a zoological garden had gross hepatic enlargement with extensive ill-defined white foci. Microscopically, the hepatic lesions were composed of a mixture of adipocytes and myeloid cells. The goose was also affected with systemic amyloidosis and there were areas of osseous metaplasia associated with deposition of amyloid within the liver. Ref
Case 3: Hepatic myelolipoma with systemic amyloidosis in a Goose A goose died suddenly following the short history of weakness and greenish diarrhea. At necropsy, multiple yellowish-white foci were observed on the surface of the prominently enlarged liver. Histologically, there were multiple foci of adipose tissue admixed with myeloid elements in various proportions in the liver as well as amyloid deposition in several organs including the liver, intestine, spleen, kidney, and ovary. Ultrastructurally, erythroblast-like cells and myelocytes, which showed various stages of differentiation, were observed in the foci of the liver. Ref