Spontaneous glomerulonephritis in dogs. I. Classification and immunopathology.

A morphological study of kidneys of 101 dogs with and without clinical signs of renal disease was done. In 90% of the dogs there was morphologic evidence of glomerulopathy. Types of glomerulonephritis were: membranous, 26 cases (with spikes, six cases; without spikes, 20 cases); membranoproliferative, 30 cases (with mesagial proliferation, nine cases; with mesangial sclerosis, 21 cases); mesagial-proliferative, 16 cases; and mesangial-sclerosing, 19 cases. There was no linear immunofluorescence indicative of autoantibodies to the glomerular basement membrane. Membranous glomerulonephritis with spikes was associated with coarse subepithelial deposits of IgG and C3. Membranous glomerulonephritis without spikes often had a linear fluorescence pattern of C3. In membranoproliferative glomerulonephritis, there were subendothelial deposits of IgG and C3, and frequently C3 deposits were within the mesangium. Mesagial deposits of C3 were frequently found in kidneys with mesangial-proliferative and mesagial-sclerosing glomerulonephritis and glomeruli that histologically appeared normal.