Objective—To study the musculoskeletal development
of Great Dane puppies fed various dietary concentrations
of calcium (Ca) and phosphorus (P) in
fixed ratio by use of dual energy x-ray absorptiometry
(DEXA), determination of serum insulin-like growth
factor I and parathyroid hormone concentrations,
radiography, and blood chemistry analysis results.
Animals—32 purebred Great Dane puppies from 4 litters.
Procedure—At weaning, puppies were assigned randomly
to 1 of 3 diets. Blood was collected for biochemical
analyses and hormone assays, and radiography
and DEXA were performed through 18 months of
age. Changes in body weight, bone mineral content, fat
tissue weight, lean mass, result of serum biochemical
analyses, hormonal concentrations, and radius lengths
were analyzed through 18 months of age.
Results—Bone mineral content of puppies correlated
positively with Ca and P content of the diets fed.
Significant differences between groups in bone mineral
content, lean mass, and body fat were apparent
early. The disparity among groups increased until 6
months of age and then declined until body composition
was no longer different at 12 months of age.
Accretion rates for skeletal mineral content, fat, and
lean tissue differed from each other and by diet group.
Conclusions and Clinical Relevance—Ca and P concentrations
in the diet of young Great Dane puppies
are rapidly reflected in the bone mineral content of
the puppies until 5 to 6 months of age, after which
hormonal regulation adjusts absorption and excretion
of these minerals. Appropriate Ca and P concentrations
in diets are important in young puppies < 6
months of age. (Am J Vet Res 2002;63:1036–1047)