I switched my dogs diet to a protein dog food when he had cancer. He was noticeably craving salmon and so I started giving him raw salmon, canned salmon and salmon protein dry dog foods. He had a soft tissue sarcoma on his front leg. He had two surgeries to remove the tumors and then was told a third surgery would do more harm than good and he was given 6 to 9 months to survive. He lived 3 1/2 more years. Wondered if the salmon diet helped and if some dog foods are causing cancer. What other environmental causes would you blame that could effect dogs? It seems diet would be the obvious one.