Stiftung Tierärztliche Hochschule Hannover Die ontogenetische ...

Studie II: Shift of the CoM in growing dogs
Treadmill speed had to be matched more or less to the preferred speed of the
dogs (i.e., the speed at which they trotted most comfortably) in order to record as
many valid strides as possible. Because absolute speed cannot be compared among
different-sized individuals, Froude number (U) was calculated using the equation (4):
(4) U = v2/g*l
v represents absolute speed (in m/s), g is gravitational acceleration (9.81 ms-2)
and l is hindlimb length (based on Alexander and Jayes, 1983).
To evaluate the change in trunk shape, the diameters of the thorax and the
abdomen were measured in the photographs using Adobe PhotoShop Version 5. The
thoracic diameter was determined posterior to the forelimb at the deepest point of the
sternum; the abdominal diameter was measured cranial to the prepuce (Fig. 1).
Then, the ratio of the two lengths was calculated. A ratio of 1.0 indicates a
rectangular area in the image (i.e., a cylindrical trunk shape), while a ratio >1.0
indicates a trapezoid (i.e., a conical trunk shape with the abdominal diameter being
smaller than the thoracic one).
Statistics
The data were tested for normal distribution using the Kolmogorov-Smirnov-Test.
Differences among the vertical force or the stance duration ratios as well as the
thorax-to-abdomen ratio and the ages were tested using a one-way analysis of
variance (ANOVA) for repeated measures followed by post hoc Tukey test. P values
of p