SPONTANEOUS LIPOPROTEIN GLOMERULOPATHY-LIKE NEPHROPATHY IN A SQUIRREL (SCIURUS VULGARIS).

Lipoprotein glomerulopathy (LPG) is a rare human glomerular disease caused by abnormal lipid metabolism. Naturally occurring LPG has not been reported in animals. We describe the histopathological characterization of spontaneous LPG-like nephropathy in a captive squirrel ( Sciurus vulgaris ). Macroscopically, swollen glomeruli were distinctively identified as fine white granules in the renal cortex. Histologically, most glomeruli were markedly enlarged with distended capillaries containing faintly eosinophilic and amorphous materials. The amorphous material was negative using the periodic acid-Schiff reaction, periodic acid-methenamine silver stain, or Masson's trichrome stain. Sudan III staining revealed lipid in the materials, and immunohistochemistry demonstrated that the material additionally contained apolipoprotein E. Electron microscopy showed numerous lipid granules and vacuoles of various sizes in the capillary lumina associated with foot process effacement of podocytes. These pathological characteristics bear some resemblance to those of human LPG.