Q. Once a dog's kidneys stop working well enough to concentrate the urine, how fast does it normally progress to more serious side effects?
A. The answer is 'No one knows'. Malfunctioning kidneys can stay at stable level for long time (months to years) without signs of kidney failure. However, kidney performance can suddenly deteriorate at any time.
It would be advisable to run blood test for kidney profile to better assess his disease.
I would suggest you to got to www.iris-kidney.com for all information you need to know about kidney problems in dogs and cats.