Membranoproliferative glomerulonephritis in a calf with nephrotic syndrome.

A 2-month-old Japanese black calf was presented with a history of weight loss, exophthalmos and subcutaneous oedema of the brisket. Urinalysis and serum biochemistry showed proteinuria and hypoproteinaemia suggestive of nephrotic syndrome. Microscopically, lesions in the kidney were characterized by proliferation of mesangial cells and diffuse thickening of the glomerular basement membranes with the appearance of double contours. Immune complex deposits were confirmed by electron microscopy and immunofluorescence using reagents specific for bovine immunoglobulin G, complement factor C3 and bovine viral diarrhoea virus (BVDV). Consequently, the glomerular lesion in this case was diagnosed as membranoproliferative glomerulonephritis. BVDV type 1 was detected in serum by nested reverse transcriptase polymerase chain reaction. Viral antigen was also identified in the glomeruli by immunofluorescence. These results suggest that BVDV may have been the cause of immune complex glomerulonephritis in this calf.