Minimal change disease of the kidney in a young Sprague Dawley rat.

Minimal change disease (MCD) can be experimentally induced in rats, but spontaneous cases have not been reported. Herein, we present a case of MCD in rats that resembled the phenotypes of human MCD. A 9-week-old male Sprague Dawley rat developed continuous albuminuria for 2 weeks and was sacrificed at 11 weeks of age. Histological testing revealed no glomerular or renal tubular abnormalities on light microscopy. Immunofluorescence revealed absence of immunoglobulin G or immunoglobulin M deposition in the glomerulus. Extensive foot process effacement of glomerular podocytes was observed by electron microscopy, with rearrangement of the actin cytoskeleton at the base of the fused foot processes. The rat did not show desmin-positive podocytes, and the nephrin showed a normal liner pattern of distribution along the glomerular capillary loop throughout the glomeruli. These pathological characteristics corresponded to those of human MCD, and the glomerular lesion was considered a rare case of rat MCD.