My poor old girl is 11 and in congestive heart failure
She can only eat boiled hamburger with white rice mixed in. Apparently this mixture is healthy for the dog, enough to sustain her, and very easy on a dog's stomach. She use to have blood in her stool, that's gone now.
She was fed, along with my previous dogs who lived quite long, a raw egg, plain cooked fish, plain cooked chicken breast, and some red meat every now and again. I never bought dog food for any of my pets.