kidney disease doesnt cause pain, but the progressive symptoms do.
Those mainly are: nausea and disorientation.
Its mostly an issue of "quality of life" instead of physical pain because at some point your cat is going to be refusing all food.
You don't need to put her to sleep yet. If she's eating and mobile.
Most important and effective treatment in slowing down kidney disease is IV and sub-q fluids! (as well as diet change). The more she drinks and urinates, the better so it flushes the toxins out of her kidneys.
it is rare for cats and dogs to live a year after being diagnosed with kidney disease because usually there aren't enough signs to catch the disease in it's very beginning. And once damage is done to the kidneys, it cant be reversed.
if you dont put your cat to sleep, kidney disease causes high blood pressure. This causes seizures. At some point, depending on how bad she is now it can be weeks, months or years, but at some point she'll die from multiple seizures. The animal is not conscious during them. Nausea at night is a sign of impending seizures.
i'd talk to your vet about giving your cat sub-q fluids yourself at home.
also, change her diet asap. Each day she's eating food not specialized for kidney disease is damaging her kidneys more..
heres a helpful site http://www.felinecrf.com/
No even though she keeps herself hydrated, she needs more fluids. It's for flushing out her kidneys, it's equivalent to human dialysis to treat kidney disease, the dialysis for humans flushes out the toxins in the blood that the diseased kidneys can't get out on their own. The extra sub-q and IV fluids used for animals, will flush out your cats kidneys, because even though she drinks fine and isn't dehydrated, the kidneys arent functioning good enough. Extra fluid forces them to flush out more toxins. If the toxins aren't flushed out, they go to the animals brain and cause the nausea/disorientation/dizziness/ decreased appetite, and they go to the heart causing high blood pressure and seizures.
So the more you flush out, the longer your cat will live and have less intense symptoms
For kidney disease, low phosphorus diet is important for cats, low protein also has shown it helps. They dont like the taste. But it's a longer, healthier life over taste.
Wet food is better for them (and even cats without kidney disease) because it will give more water. Mine liked the dry better though.
There is plenty of research that shows low phosphorus and protein diet help, it balances electrolytes that are out of wack from the kidney disease. The predominant effect of the low protein diet is to minimize production of uremic toxins so that the patient feels better.