Hello, I'm sorry to hear that your pup is in renal failure and I'd like to help.
Do you know what precipitated this episode?
It is helpful to know the cause if we can determine it, as that will direct treatment. For example if this is related to an infection with a bacteria called Leptospirosis then antibiotic therapy and fluids can be tremendously helpful.
Infectious causes generally respond better to therapy, if we treat the infection the kidneys have a chance of coming back.
However if this is a progression of chronic renal failure then the prognosis becomes much more guarded.
So ideally testing should be done, including: cultures of his urine, testing for leptospirosis if your veterinarian feels he is at risk of exposure, blood pressure measurements as if he is hypertensive then treating that will help his kidneys, urine tests to look for excess protein spillage as if he is spilling protein there are medications like enalapril or benazepril (especially if he is hypertensive too) that can help.
Dietary supplements like Azodyl, which helps control gut bacteria that contribute to high levels of uremia, and Epakitin, which binds phosphorus if his blood levels of that electrolyte are increased, and omega 3 fatty acids to reduce inflammation, can be very helpful.
Of course feeding a kidney support diet like Hills k/d or Royal Canin Renal Diet is recommended. These foods are formulated to support kidney function and not overstress them with levels of protein that are too high.
Fluid diuresis is very important, and is the mainstay of treatment in kidney failure. He may need to be on fluids long term if we cannot get his kidney waste enzymes down and keep them down.
I understand that you want to help your dog as much as you can, hopefully the suggestions I've given you will help. Please let me know if you have any further questions.