Some unusual features of mesangioproliferative glomerulonephritis in horses.

Seven horses ranging from three to 15 years of age had nephrotic syndrome; at necropsy, renal tissue of all seven horses had the morphologic lesions of mesangioproliferative glomerulonephritis (membranoproliferative glomerulonephritis). Homogeneous eosinophilic material which filled the glomerular capillary lumina was found in five horses. Ultrastructurally, this material primarily consisted of electron-dense deposits with a fibrillar pattern in five horses and in one horse, rhomboid crystalline deposits which resembled deposits seen in human cryoglobulinemia. The association of mesangioproliferative glomerulonephritis with cryoglobulinemia is well documented in man. The presence of intracapillary deposits, with the histologic and ultrastructural lesion of mesangioproliferative glomerulonephritis, suggests a similar association in these horses.