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Other Names: Avian Amyloidosis, Amyloid Arthropathy, AA Amyloidosis (AAA)
Avian amyloidosis is a fatal progressive disorder which occurs commonly in adult birds, especially chickens. The disease involves the build up of an abnormal protein (amyloid) within cells in various tissues and organs in the body. Although amyloid deposition can occur in any tissue, it most commonly occurs in the liver, intestine, kidney, and spleen.
There are several types of amyloidosis that occur in humans, however, birds are most frequently affected by the inflammation-associated form---also known as AA‐amyloidosis or systemic amyloidosis.
Amyloidosis is frequently associated with an underlying infection or inflammatory condition, such as bumblefoot, gout, avian tuberculosis, or tumors. This is because prolonged inflammation causes a significant increase in serum levels of the hepatic acute phase reactant serum amyloid A (SAA), the precursor protein of amyloid protein A (AA).
Brown egg-laying hens are highly susceptible to amyloid arthropathy as a result of Entercoccus faecalis and Mycoplasma synoviae infections. E. coli, Salmonella enteridis, and Staphyloccus aureus have also been associated with amyloidosis in chickens.
How is Amyloidosis Diagnosed?
Since clinical signs of amyloidosis are non‐specific, diagnosis requires histopathology following biopsy or necropsy.
Once deposition of amyloid into the cells has started, progression of the disease is irreversible. However, the incidence and severity of amyloid arthropathy can be reduced through treatment with methylprednisolone. Methyprednisolone significantly inhibits fibrillogenesis by lowering both heterophil and macrophage infiltration. Birds should not receive any supplemental Vitamin A, as studies have shown it increases the development and severity of Freund’s adjuvant-stimulated amyloid arthropathy by increasing the levels of SAA.
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: Fowlpox with amyloidosis in a Chickens Cutaneous fowlpox occurring in vaccinated layer hens was investigated pathologically and microbiologically. Anorexia, decrease of egg production, increased mortality, yellow scabs on faces, and alopecia of feathered skins with yellow scabs were observed in affected hens. Histologically, proliferative and necrotic dermatitis with eosinophilic ring-shaped cytoplasmic inclusions (Bollinger bodies) and clumps of gram-positive cocci (Staphylococcus hyicus) were noted in the affected birds. Fowlpox lesions were primarily observed in the feathered skins. Proliferation of feather follicle epidermal cells, with cytoplasmic inclusions and degeneration of the feather, and bacterial clumps in the feather follicles were noted in the affected skins. Ultrastructurally, characteristic fowlpox viral particles were observed in the cytoplasmic inclusions of hyperplastic epidermal cells. Amyloid deposition was observed in the Disse space of the liver, splenic sinus, and lamina propria of the bronchiolar, bronchial, and tracheal areas. Amyloidosis could be one factor inducing the fowlpox infection in vaccinated chickens. Ref
Case 3: 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 4: 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