The objective of this study was to investigate IGF1R expression in a large cohort of canine invasive carcinomas, focusing on its relationship with the clinicopathological features and prognosis, in terms of overall, specific and disease-free survivals, in order to evaluate the similarities between the role of IGF1R in the canine species and those previously reported in human breast cancer. The gene discussed is IGF1R; the disease is invasive carcinoma.