I'll share our story and maybe it will be of some help to you. We lost our Sadie in July after battling kidney disease for two years. We discovered her values were off by accident (a bout of the big D that wouldn't go away). We began by monitoring her values frequently. We gave her baby aspirin. But after some research I decided to stop. Medication (Enalipril) was eventually added, and eventually increased. Eventually our vet suggested we needed to adjust her diet. We chose Iams early stage renal. She was 11 when all of this began. We cooked the wet portion of her diet.
She did well until sometime last year, early 2010 when things changed. At first the changes are subtle and we didn't notice because we lived with them everyday. She had lost some weight but it started going down steadily despite her eating (she was a picky eater though) about 4 cups a day. She stopped running and would just sometimes trot on her long walks around our property. She started getting up in the middle of the night to go outside. Sometimes more than once. Eventually she was no longer phased by loud noises that used to scare her so. Gunshots in the area from hunters didn't phases her nor did fireworks (but thunderstorms still made her a little nervous). I chalked it up to old age. She shortened her walks but still took them. She stopped greeting visitors. Barely acknowledged them. She was a people dog. She was having this twitching through her whole body. A shivering. But she didn't stop when we kept her in PJs. It was neurological.
Our vet said it was a race between her kidneys and weight. We could no longer keep the weight on. She was dropping it like crazy. Eventually She had lost so much muscle mass that she was having trouble standing and would be weak in the rear like a German Shepherd. But, she seemed happy to come down the driveway, she would stand as best she would and get excited. She liked her walks, even though there was no more running or trotting. She had not messed in the house. She was still eating. She seemed to still be having some enjoyment. And she seemed aware. But we knew the end was near, just not when exactly. We weren't going to put her through anything diagnostic because we wouldn't put her through any procedures to prolong her life. She was 13 and we wanted her as happy and comfortable for as long as possible. When she was no longer, then we knew it was time.
We kept visiitng the vet weekly for weight checks. When she got to 50lbs (from 65lbs 9 months before) we stopped. She had lost as much as 5lbs in a month. It was getting too upsetting. For her and for us. She would panic at the vet's even though everyone liked to see her and she wasn't even poked or prodded anymore. The vet gave her prednisone to help with her ability to stand. It did help. That was June. July 10 she had probably gotten down to 45lbs, maybe less. We had fenced the top part of the yard that day to restrict her movement because she could no longer walk up/down the bank in the yard. She pooped that afternoon. She was just staring, not evening blinking. Just waiting for something. Her breathing was even strange. July 11 she would not settle down. Her front legs looked swollen. I feared edema.
We called the vet the next morning. We took her in that afternoon. He always would roll his eyes at my millions of concerns - but this time his say his face said it all. He was stunned at the change in her in a month. He examined her quickly and said it was time to discuss euthanasia. But we already knew and had come prepared with questions. He was leaving for Europe on Wednesday. It was Monday. He had Tuesday off. We asked if he could come to the house. It didn't seem real. But she hadn't eaten anything but hand fed scrambled eggs since the 10th, and hadn't defecated since the 10th. She had lived 13 good years.
I do not pray. But I did that morning- for a sign I was doing the right thing. And she went happily for her walk. She moved better than she had in weeks. Her tail was curly and she sniffed and enjoyed herself. I saw the vet pull into the driveway, wondering where we were no doubt. I decided to go tell him to leave. Then she had a bowel movement. It was black and tarry and gooey. She was bleeding internally. I knew it was time. We brought her into the backyard. We said goodbye. It was as peaceful as you could hope for. Awful of course. But I am glad that we spared her any horrible days. She had only days left. I struggled though in the beginning that we did it too soon. But I talked to the vet and to many other dog owners. My vet believes she had some type of cancer as well. I am at peace with our decision.
And we recently adopted a red boy we named Kevin.
My advice is do whatever it takes to keep/put weight on. Ultimately that may take her. Take her to another vet if you are unsure about any part of the diagnosis. But you know her best. You know when she is no longer herself and is no longer enjoying anything.
My sympathy to your family as you face each day determining your next steps.
Also, my condolences to Maggie's family.