Light and electron microscopic observations on glomerular changes in canine interstitial nephritis

Light and electron microscopic studies on dogs suffering from chronic interstitial nephritis revealed glomerular lesions characterized by thickening of the glomerular capillary walls and an increase in the mesangium. The thickened capillary walls stained strongly with PAS stain and less with silver methenamine stain. Electron microscopy revealed the presence of subendothelial and occasional subepithelial electron dense deposits in the thickened and split glomerular basement membrane. Degenerative changes were seen in the epithelial as well as in the endothelial cells. Similar but milder lesions were seen in clinically healthy old control dogs but not in young healthy dogs. The findings emphasize the importance of glomerular lesion in canine interstitial nephritis and supports the hypothesis that an altered immunological mechanism, probably related to ageing, might be pathogenetic in this disease.