Carla Appelgrein

Objective: Document the highest extension angle of the carpus and quantify the ground reaction forces observed during entrance of the A‐frame at three incline angles. Methods: Kinematic gait analysis measuring carpal extension was performed on 40 dogs entering the A‐frame at 40°, 35° and 30° incline. The average of the highest carpal extension angle from each of three trials at each incline was examined for a significant effect of incline, including covariates of dog height, body weight and velocity. Kinetic gait analysis was performed on 8 dogs of similar body morphology entering the A‐frame at 40°, 35° and 30° incline. Vertical and cranio-caudal ground reaction forces were normalized and averaged from three trials at each incline and examined for a significant effect of incline, including covariates height and velocity. Results: The highest carpal joint extension angle did not differ statistically between the three A‐frame angles of incline for the first or second limb. The covariate-adjusted mean carpal extension angle for the first limb at 40° was 64° (95% CI 60‐68). Regarding the cranio-caudal forces, the peak propulsive force and the proportion of time spent in propulsion (%) were significantly higher at 40° incline compared to 30°. There was no significant effect of incline on the vertical ground reaction forces. Conclusion: Decreasing the A-frame incline from 40° to 30° did not reduce carpal extension angles. The failure to find a difference with narrow confidence intervals may indicate the physiologic limit of carpal extension was reached. Ascent up the A-frame at 40° requires a higher propulsive force combined with extended time spent in propulsion to maintain forward movement. Future research should examine the effect of repetitive loading with A‐frame contact on the limits of physiologic carpal extension.