BACKGROUND: With hydrotherapy rising in the United Kingdom, before understanding the effect of hydrotherapy in animals with pathologies, kinematics data for healthy animals is required. OBJECTIVES: To assess how different water levels on an underwater treadmill (UWTM) can affect joint kinematics. METHODS: Zinc oxide markers were placed on bony landmarks on the limbs of 10 healthy dogs, randomly split into five groups. An UWTM was used with water levels to the digits, tarsus, stifle and hip. The maximum flexion, extension and ROM were determined and a repeated measures ANOVA or Friedman's was used to determine significant differences. RESULTS: We have detected various changes in kinematics following exercise at different water levels, in comparison with a dry treadmill, including consistent increases in flexion of the elbow, stifle and tarsal joints, which were observed for all water levels. The carpal joint had increases in flexion all water levels apart from digit level. An increase in shoulder flexion was seen only with water on or above stifle level, while hip kinematics had the fewest changes with only ROM increasing at high water level (hip level). Extension of the limbs joints was not markedly affected, with only a few data being significant. The carpal joint had an overall decrease in extension with water at all levels, and the stifle joint had a decreased extension when water was at stifle height. CONCLUSIONS: Water level can significantly affect joint kinematics, and knowledge of how each water level affects the joints is relevant to design tailored hydrotherapy protocols.