A female 8-year-old Pug weighing 7.3 kg and a female 10-year-old Maltese dog weighing 3.5 kg showing anorexia and vomiting for a few weeks were referred to Veterinary Medical leaching Hospital, Seoul National University. Radiographic findings were an enlarged right kidney in a pug dog and a radiopaque material on the right ureteral region lateral to the third lumbar vertebrae with indefinite right kidney contour in a Maltese dog, repectively. Excretory urography performed in a Pug dog revealed a poor opacified enlarged right kidney with absent of pelvic recesses and pelvic dilation with proximal ureteral dilation on contralateral kidney. Ultrasonographic findings were enlarged kidney with dilated pelvis and echogenic sediment within the medulla in both dogs and especially an engorged proximal ureter and a thin rim of functional renal tissue remains in a Maltese dog. Those diagnostic findings indicated high possibility of pyelonephritis and these were confirmed by pathologic examination. Radiography and ultrasonography, although not giving final diagnosis for pyelonephritis, are useful for assessment and diagnosis of pyelonephritis.