Insulin-like growth factor I levels in proportionate dogs, chondrodystrophic dogs and in giant dogs.

Plasma insulin-like growth factor I concentrations from proportionate, chondrodystrophic and giant breeds were evaluated and compared with body size. IGF-I plasma concentrations were 91.2 +/- 10.9 micrograms/l in Keeshounds (proportionate dog), 122.6 +/- 25.4 micrograms/l in Bassethounds (chondrodystrophic dog) and 280 +/- 22.8 micrograms/l in German Shepherds (proportionate dog). The highest IGF-I level (389.6 +/- 24.2 micrograms/l) was found in the New Foundland, a giant breed (mean +/- SEM). The mean body weight was 11.8 +/- 0.4 kg in Keeshounds, 15.4 +/- 1.4 kg in Bassethounds, 32 +/- 1.5 kg in German Shepherds, and 45.6 +/- 1.7 kg in New Foundlands (mean +/- SEM). Body weight and plasma IGF-I concentration were significantly correlated (y (IGF-I) = -7.43 + 8.7 X (body weight); P less than 0.0001.