Since susceptible large breed dogs have higher IGF-1 levels (Burrow et al., 1998), and IGF-1R is often overexpressed in canine osteosarcomas (Eigenmann et al., 1984; Sutter et al., 2007), a link between IGF-1 signaling and osteosarcoma has been proposed. This evidence concerns the gene IGF1 and osteosarcoma.