Investigation on skeletal development in small-sized breed newborn dogs: anatomic and radiographic findings obtained by spontaneously died animals

Species-specific measurements and ranges for normal skeletal growth are reliable reference data for various studies, including those related to age determination and disorders of growth and nutrition. In dog, limited information is available about normal skeletal growth characteristics and when present, they refer mostly to Beagles as animal model (Helmsmuller, 2013). Because of the great number of pure breed dogs the main limitation of these studies relies on the need of homogeneous and sizeable populations; moreover each subject must be submitted to serial and multiple investigations that, although weakly invasive, are inadvisable in puppies, according to animal welfare rules. Finally, some analyses are not possible on living individuals. In this research we considered the possibility of using 27 remains of spontaneously died puppies (0-28 days) as a consistent population to study the skeletal development of small-sized breed dogs during the first month of life. These puppies belonged to different pure breeds and were categorized according to the standard breed adult body weight < 7 kg (Brianza, 2006). Anatomic and radiographic measurements of limb bones length and of skull diameters were positively correlated with weight and age of the subjects and weight was positively correlated with radius bone mineral density (Spearman bivariate test, P<0.01). Histological evidences confirmed the presence of the limb secondary ossification centres observed by x-rays and detailed the onset of their formation. These data suggest that cadavers of young animals may represent a useful tool to study skeletal development and possible disorders in dog.