http://www.canismajor.com/dog/iamssym1.html#KIdney
For years, physicians and veterinarians have treated renal failure by
reducing protein levels in diets,' said Gregory Reinhart PhD, an Iams
researcher. 'After working with leading universities, we have now found
that restricting protein in a dog's diet may do more harm than good by
potentially putting the companion animal at risk of protein malnutrition.'"

These articles have moved and I haven't been able to track them down......

Dogs with kidney problems by Dr. Lucy Pinkston, D.V.M.
"Because by-products of protein digestion are the main toxins that need
to be excreted by the kidneys, an obvious assumption might be that all
one needs to do is to cut out the protein and the kidneys wouldn't have
any more hard work to do.... There is significant evidence, however,
that the daily protein requirements actually increase slightly for dogs
in chronic renal failure. Therefore, severely restricting the protein
for such a dog is likely to result in protein malnutrition, in spite of
the fact that the levels of blood urea nitrogen, or BUN (the primary
by-product of protein metabolism) would be correspondingly lower."


http://www.speedyvet.com/NIP/olddogs/default.htm
"The assumption was that low-protein diets retarded the progression of
renal degeneration. This assumption was disproved, using partially
nephrectomised dogs, which showed no uraemic signs and had reduced but
stable renal function for 48 months. These dogs did better on
moderate-protein diets than on low-protein diets. There is no direct
evidence that high protein intake damages canine kidneys or that
reducing protein intake in dogs with renal dysfunction results in
preservation of either renal structure or function."

[Posted in FML 5436]