Spontaneous glomerulonephritis in dogs. II. Correlation of glomerulonephritis with age, chronic interstitial nephritis and extrarenal lesions.

A morphologic study of 103 dogs, including two with renal amyloidosis, showed that different types of diffuse glomerulonephritis are correlated with different age groups. Membranous and membranoproliferative glomerulonephritis were more common in middle-aged and older animals, whereas mesangial lesions were found predominantly in younger dogs and considered to be early glomerular changes. Glomerulonephritis largely occurred independently of interstitial nephritis. The incidence of interstitial lesions was 71%. Chronic interstitial nephritis was rare in dogs under 1 year old. Glomerulonephritis did not seem to induce interstitial nephritis. Glomerulonephritis occurred not only in kidneys with severe interstitial damage, but also in those with slight damage. The indicated that glomerulonephritis occurred independently of interstitial nephritis. In end-stage kidneys with severe fibrosis, mesangial changes seemed to predominate.