Under Developed Kidneys

Question
My dog is a Shih Tzu/Pom mix weight15lbs. and is
2 years old.She is my baby.She is not sick at all eats good and plays hard.She was showing signs of a problem with her back leg.she is carrying it alot. I took her to the vet and xrays showed something wrong with her hip.When he did her blood work before surgery it showed something wrong with her kidneys. So he didn't do the surgery .
After a ultrasound and lab work he said she had under developed kidneys and they were only working at 20%.I know no one knows for sure how long she can live before she may have some real bad problems with her kidneys. Do you have any experience with this and how long the life expectancy is.I will greatly appreciate any information you could give me .Thank you Sandy

Answer
It is difficult to determine life expectancy in this situation and I really do not have experience with congenital kidney disease, just old-age kidney failure.  I would recommend a urine culture to rule out an underlying kidney infection and maybe even consider a kidney biopsy which could give a better idea of prognosis.  I would definitely recommend feeding Hills K/D food to help ease the work-load of her kidneys as this diet has been studied to extend the life of pets with kidney disease.