A case of juvenile nephropathy in a two-year-old male Boxer is reported. Clinical aspects, blood analysis, renal pathology and extrarenal changes are described. The renal changes mainly consisted of tubular and glomerular atrophy, tubular swelling, tubular and glomerular hyaline casts, mineralization, glomerular basement membrane thickening and capsular fibrosis. The main extrarenal lesions, which consisted of a necrotizing inflammatory reaction, were localized in the endocardium and myocardium, as well as in the aorta and truncus pulmonalis. Additionally, a septicemia linked to a localized purulent inflammation in the neck was noted.