Triple amyloidosis involving fibrinogen Aα-chain, apolipoprotein A-I and EGF-containing fibulin-like matrix protein 1 in an aged dog.

Amyloidosis is a group of disorders characterized by the deposition of misfolded proteins within the body, with disease subtypes classified based on the precursor protein. With the increasing longevity of captive animals, several forms of age-related amyloidosis have been reported in recent years, and attention to this disease in the welfare of aged animals has been growing. Here, we report a case of amyloidosis in a 14-year-old Shetland Sheepdog involving three age-related amyloid types. Histopathological analysis, mass spectrometry-based proteomic analysis and immunohistochemistry revealed fibrinogen Aα-chain-derived amyloid deposited in the vascular walls of the liver, glomeruli of the kidney, cardiac mitral valve, coronary artery walls and myocardial interstitium; apolipoprotein A-I-derived amyloid deposited in pulmonary vascular walls and alveolar septa; and EGF-containing fibulin-like matrix protein 1-derived amyloid deposited in the submucosa and vascular walls of the gastrointestinal tract. All three of these amyloidoses have been documented as age-related amyloidosis in animals, suggesting that ageing may also have contributed to the development of triple amyloidosis in this case. This study highlights the diversity of amyloidosis in aged dogs and emphasizes the importance of accurate organ-specific typing of amyloids.