I would work closely with the veterinarian that is treating your dog. I would imagine the vet has recommended soft canned prescription food.
As a senior, your dog has multiple issues, I think the best you can do is to do exactly as the veterinarian advises, prescription meds and all, the goal is too keep her comfortable for the time she has left. Make sure she has fresh water available 24/7, add water to her food.
She won’t eat her feces if you stay with her when she is due to eliminate, scoop and discard immediately.
For anyone to advise you to do anything different than from what a veterinarian that has examined the dog recommends, is irresponsible and those actions may most likely increase the dog’s discomfort and pain.
Call the vet and discuss her symptoms, evaluate your options.
Good luck.
