Dont do that, please. My 17 years old siamese kiki was taken away from me by renal disease 5 months ago. The last 4 months were terrible. She was blind and barely made it to the box. My mother was the worst at that time and was looking for excuses to put her down. She also refused to have multiple boxes or anything that could have made my cat's life easier. (Sorry, im just venting, but fuck my psycopath mother, freaking loony).
I'm in peace knowing that i and my brothers did everything we could to make kiki feel loved to the last minute.