You could try green tripe (cow's stomach lining). It is pretty nasty, but it is recommended to people for dogs with a lack of appetite. My dog is young, but it took me close to a year to find a food that she would eat for more than a couple meals. The brand is Nature's Variety. It is frozen, raw food. Some dogs aren't fans of the raw food, but she absolutely loves it. Before feeding it to her, I would have to start hand feeding her, bring her dish into the living room, and many other crazy things to get her to eat. If you can't find the Nature's Variety frozen, raw meat, you could try other brands of pre-made frozen or try your own raw feeding. Feeding your own raw entails the addition of many nutrients, though, so you would need to do some research. However, you could at least try feeding her a few bites of raw burger, steak, chicken, turkey, etc. just to see what she thinks of it. Good luck. I know how frustrating it can be. I went through it with my current dog (as told in this message). I also went through it with a dog who had an overly hearty appetite her whole life but lost her appetite during kidney failure. It's not fun.