[The effect of a different energy supply on the growth intensity and skeletal development of growing Great Danes. 2. Effect on insulin-like growth factor I and on thyroid hormones].

In an experiment with 13 growing Great Danes (littermates) fed ad libitum (4 dogs) or restrictively (70% of ad libitum energy intake; 9 dogs), concentrations of insulin-like growth factor I (IGF-I), 3,5,3'-triiodothyronine (T3) and thyroxine (T4) were measured in blood samples until the age of 6 months. In the ad libitum fed group, levels of T3 and T4 were partially and of IGF-I were significantly (p < 0.01) elevated as compared with the control dogs. Postprandial changes of IGF-I were absent in growing Great Danes as well as in a reference group of 3 adult beagles. Increased concentrations of IGF-I, T3 and T4 could be causally related to osteochondrosis, which frequently occurs in intensively fed dogs.