Non-neoplastic renal lesions in Sprague-Dawley and Fischer-344 rats.

Incidences of non-neoplastic renal lesions in untreated Sprague-Dawley (1540) and Fischer-344 (491) rats were evaluated, tabulated, and compared. In Sprague-Dawley rats, the most frequently occurring lesion was chronic progressive nephropathy (68.5%) followed by tubular mineralization (30.9%), pelvic calculi (9.0%), brown pigmentation of the tubular epithelium (8.8%), hydronephrosis (5.1%), tubular dilatation (3.1%), and vascular mineralization (3.1%). In Fischer-344 rats, chronic progressive nephropathy (82.0%) was the most commonly occurring lesion followed by tubular mineralization (38.8%), vascular mineralization (2.2%), hydronephrosis (1.6%), and pelvic calculi (1.4%). In both strains, other lesions were less frequent.