As far as I know, kidney transplants don't work very well in dogs. Cats yes, dogs no, I'm so sorry
I guess the question is what the status of the kidney function is now, and I would go for a kidney friendly diet - personally I would not feed commercial food, but would feed a homecooked diet put together by someone like Monica Segal or Sabine Contreras.
Best of luck to you, this is so difficult.
