The normal standards for ultrasonography renal characteristics and dimensions and thickness of cortical and medullary regions in healthy animals can be used for identification of renal alterations. The study aimed to analyze and compare the ultrasound characteristics and dimensions of the kidneys, evaluating the significant difference in renal measurement between healthy puppies and kittens. Fifteen healthy puppies with mean weight of 3 kg and 15 healthy kittens with mean weight of 2 kg, cross breed, and aged between 5 and 6 months were included in this study. All animals underwent renal ultrasound for visualization of internal characteristics and assessment of renal length, cortical and medullary thickness, and corticomedullary ratio. The renal margin was not observed in puppies but was observed in 50% of kittens. The renal cortex in puppies was visualized with similar echogenicity to the spleen. The ultrasound measurements between the left and right kidney in puppies and kittens have showed no significant difference. The ultrasound measurements of kidneys between puppies and kittens showed a significant difference. The puppies' kidneys, right and left, tend to be bigger in length (5.18 ± 0.01 cm/5.16 ± 0.01 cm), cortical thickness (0.74 ± 0.02 cm/0.74 ± 0.01 cm), medullary thickness (0.74 ± 0.02 cm/0.74 ± 0.01 cm) in relation to renal length (2.98 ± 0.01 cm/2.92 ± 0.02 cm), cortical thickness (0.33 ± 0.01 cm/0.32 ± 0.01 cm), medullary thickness (0.32 ± 0.02 cm/0.31 ± 0.02 cm) in kittens. However, the corticomedullary ratio (PCM) was similar in both groups.