Systemic fibrinogen Aα-chain amyloidosis in 3 Japanese raccoon dogs

Systemic fibrinogen Aα-chain (FibA) amyloidosis—in which amyloid is deposited in renal glomeruli and the heart—has been reported in humans, Japanese squirrels, and dogs. Here, we describe systemic FibA amyloidosis in 3 aged Japanese raccoon dogs ( Nyctereutes procyonoides viverrinus ). Histologically, we observed marked deposits of amyloid in the renal glomeruli and cardiac arterial walls. Liquid chromatography–tandem mass spectrometry-based proteomic analysis of the amyloid deposits, together with immunohistochemistry, identified the αC-domain of FibA as the major component of the amyloid. Given that all affected individuals were aged (>12-y-old) and genetic analysis revealed no amino acid mutations in FibA, aging may have contributed to disease development. The deposition of αC-domain–derived FibA amyloid in the renal glomeruli and heart in Japanese raccoon dogs resembles that reported in Japanese squirrels and dogs, suggesting a conserved pathogenic mechanism across species.