Stiftung Tierärztliche Hochschule Hannover Die ontogenetische ...

Studie II: Shift of the CoM in growing dogs
Second, puppies have a relatively voluminous belly and a cylindrical rather than
the conical body form that adults show (Fig. 1). Abdominal organs such as spleen or
kidneys show negative allometry, while the heart (Lützen et al., 1976; but see
Deavers et al., 1972) and the stomach exhibit positive allometry in various mammals
(guinea pig: Bessesen and Carlson, 1923; dog: Deavers et al., 1972; Lützen et al.,
1976; rat: Stewart and German, 1999). Furthermore, to fuel ontogenetic growth and
provide the developing body with the tissue necessary for digestion and absorption of
high dietary loads, the small intestine is enlarged in growing animals. For example,
Beagle puppies at PW9 have a small intestine that is 33% longer, weighs 45% more,
has 40% more mucosa and 35% more surface area compared with adults (Paulsen
et al., 2003). Taken together, the growth patterns of the inner organs and particularly
of the small intestine are in accordance with a cranial shift of the CoM. On the
contrary, muscularity increases more in the hindlimbs than the forelimbs in cursorial
mammals such as bovids (Grand, 1991), and dogs, as other mammals, show
negative allometry of their heads (Helmsmüller et al., subm.). Nevertheless, although
the latter two observations would be consistent with net caudal shift of the CoM, our
results indicate that the growth patterns of the inner organs dominate the limb loading
changes in growing dogs.
3.7. Acknowledgments
We thank our colleagues J. Abdelhadi, S. Fischer, V. Galindo-Zamora and P.
Wefstaedt for discussions, K. Lucas for technical assistance and the animal keepers
of the Small Animal Clinic for their support.
3.8. Conflict of interest statement
None of the authors has any financial or personal relationship that could inappropriately
influence or bias the content of the paper.
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