She may develop mouth ulcers, and also ulcers of
the G.I. tract..you may see blood in
her stools. She will become more lethargic, and want to sleep for many hours. She will start to urinate less. She may have seizures, or she may go into a coma, and die peacefully. We would all want them to die peacefully in their sleep, but this is not always the case.
I have read many peoples posts on kidney failure in their dogs. Most people say that when their dog stops eating, The time is near.