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Amyloidosis
Other Names: Avian Amyloidosis, Amyloid Arthropathy, AA Amyloidosis (AAA)
Avian amyloidosis is a progressive, often fatal disease that most commonly affects adult birds, particularly chickens. It is characterized by the accumulation of an abnormal protein called amyloid within cells across various tissues and organs. While amyloid can deposit anywhere in the body, it is most frequently found in the liver, intestines, kidneys, and spleen.
Although multiple forms of amyloidosis exist in humans, birds are most commonly affected by the inflammation-associated type, known as AA (or systemic) amyloidosis.
This condition is often linked to chronic infection or ongoing inflammation. Diseases such as bumblefoot, gout, avian tuberculosis, and certain tumors are commonly associated. Prolonged inflammation leads to elevated levels of serum amyloid A (SAA), a protein produced by the liver. SAA serves as the precursor to amyloid protein A (AA), which accumulates in tissues and drives disease progression.
Brown egg-laying hens are particularly susceptible to amyloid arthropathy, often in connection with infections caused by Entercoccus faecalis and Mycoplasma synoviae. Other bacteria, including Escherichia coli, Salmonella enteridis, and Staphyloccus aureus have also been associated with amyloidosis in chickens.
Amyloidosis Diagnosis
Clinical signs of amyloidosis are often vague and non-specific, making diagnosis difficult without laboratory testing. A definitive diagnosis requires histopathological examination of tissue obtained through biopsy or necropsy.
Amyloidosis Treatment
Once amyloid begins to accumulate in tissues, the disease is irreversible. However, in some cases, the incidence and severity of amyloid arthropathy may be reduced with treatment using methylprednisolone. This medication helps inhibit amyloid formation by reducing inflammatory cell activity, including heterophils and macrophages.
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
Landman, W. J., E. Gruys, and R. M. Dwars. A syndrome associated with growth depression and amyloid arthropathy in layers: a preliminary report. Avian Pathology (1994)
