Reliability of range-of-motion measurements of healthy dogs examined while walking on a treadmill

OBJECTIVE To determine the reliability of range-of-motion (ROM) measurements and describe physiologic differences in ROM or habituation effects during gait analysis of healthy dogs walking on a treadmill. ANIMALS 11 orthopedically normal dogs. PROCEDURES ROM of appendicular joints was determined for each dog while walking on a treadmill on 3 consecutive examination days and once again 6 weeks later. Significant differences in ROM between examination days were determined and quantified. As a measure of reproducibility, the coefficient of variation for repeated measurements was calculated, as were the minimum differences necessary to distinguish between physiologic variation and true change in ROM. RESULTS Mean ROM of the shoulder, elbow, and carpal joints varied among examination days between 29.9° and 33.1°, 49.4° and 52.8°, and 7.7° and 88.1°, respectively. Mean associated minimum differences were 12.0°, 14.1°, and 35.6°. Mean ROM of the hip, knee, and tarsal joints varied between 32.9° and 35.8°, 33.7° and 36.8°, and 31.7° and 33.5°, respectively. Mean associated minimum differences were 16.2°, 14.0°, and 9.2°. Only ROM of the elbow joint was reproducible to a small degree. Few systematic effects were detected. CONCLUSIONS AND CLINICAL RELEVANCE Measurement of ROM in healthy dogs walking on a treadmill was shown to be diagnostically unreliable owing to high variation among examination days. However, random physiologic fluctuations could be distinguished from systematic effects, demonstrating the importance of reliably applicable threshold values for follow-up treadmill examinations. The applicability of the minimum differences determined here to orthopedically diseased dogs remains to be determined.