In this study we evaluated the immunohistochemical expression of ferritinophagy-related proteins, namely Ferritin Heavy chain (FTH1) and NCOA4, and proliferating cell nuclear antigen (PCNA) in canine normal bone and canine osteoblastic osteosarcoma (COOS) samples. The gene discussed is PCNA; the disease is osteoblastic osteosarcoma.