In the present study, we address systemically a case of renal disease developed in a 1 year-old male cocker spaniel dog in terms of clinical signs, clinical pathology and pathological examinations. The animal has been suffered from renal dysfunction signs such as polyuria, anorexia, vomiting, diarrhea and weight loss. The dog was very weak and emaciated and had foamy contents with foul-smell in oral cavity. The animals showed notable decrease in the number of red blood cells and severe decreases of hemoglobin and hematocrit with or without changes of mean corpuscular volume and mean corpuscular hemoglobin concentration values, indicating microcytic or normocytic hypochromatic anemia. In serum chemistry, blood urea nitrogen, creatinine, phosphorous, Na and Cl, which are associated with renal function, were dramatically increased. In addition, alanine aminotransferase, aspartate transferase, alkaline phosphatase, cholesterol, lipase and amylase were also significantly elevated, while K concentration was notably decreased. Urinalysis indicated prominent proteinuria with increase of bilirubin. Despite of symptomatic treatments, the dog was getting worse in healthy condition and dead in the end. At necropsy, both kidneys were brownish, pale, slightly small, and have diffuse, firm and subcapsular pits. Histologically, the kidneys indicated prominent segmental or diffuse interstitial fibrosis in cortex and medulla as well as glomerulonephritis. The clinical signs, clinical pathology and histopathological abnormalities of the young dog presented were consistent with chronic glomerulonephropathy, which was suspected to be a case of familial renal disease in the juvenile cocker spaniel dog.