That is a REALLY high creatinine at 27, which is actually a more significant number than the BUN when looking at the kidney values. That is about 10 times the high end of normal value. It is pretty indicative of end stage renal failure.
The sub-Q fluids will keep him hydrated and will help to reduce the BUN and creatinine somewhat, but you are not going to make him magically better with the fluids. They are to help keep him comfortable and hydrated at this point. I would say you may only have a few weeks for him to have quality of life.
I always tell my clients, you will know when it is their time to say goodbye. You need to decide for yourself what the marker is going to be for the point where you are going to stop - it may be if he refuses food for more than 12 hours, or if he refuses to drink, or if he stops interacting with family members, etc. But I always tell clients that you will know. And they usually tell me that thy *did* know when the time was right to make the ultimate decision for their pet.
I am so very sorry that you and your dog are going through this. These dogs really are members of the family.
I will be thinking good thoughts for you and your dog. :-)
Dr. Tanis!
Dog Veterinarian
10 years experience in small animal emergency medicine