Long-term renal responses to high dietary protein in dogs with 75% nephrectomy

It has been proposed that ingestion of large amounts of dietary protein leads to sustained renal hyperperfusion and progressive glomerulosclerosis in rats. This hypothesis was tested in dogs, with 75% reduction in renal mass, maintained for 4 years on either 56, 27, or 19% dietary protein. Twelve of 21 dogs survived 4 years, and death due to renal failure was not correlated to diet. Dogs fed 56 and 27% protein had increased GFR and CPAH before and after reduction of renal mass compared to the 19% group. A pattern of deterioration of renal function, including proteinuria, was not found in any diet group. Nine of 11 dogs, fed 56, 27, or 19% protein had minimal glomerular lesions, including mesangial proliferation, GBM irregularities, adhesions, and sclerosis. Two other dogs, fed 56% protein, had more severe glomerular lesions. No significant ultrastructural differences were found in glomeruli among the three diet groups. These results do not support the hypothesis that high protein feeding had a significant adverse effect on either renal function of morphology in dogs with 75% nephrectomy.