HIGHLIGHTS
• Dogs fed a food low in protein/high in essential amino acids were compared with those fed other low-protein foods.
• The experimental food group showed less progression of kidney disease and maintained lean body and bone mass.
• Amino acid profile is important when formulating low-protein foods.

Previous studies have shown that reducing dietary crude protein concentration can slow progression of kidney disease in companion animals. This experiment compared 3 commercially available geriatric foods with an experimental diet. Forty healthy geriatric beagles were randomly assigned to 1 of 4 foods (A = experimental food, B = Royal Canin Mature Medium Breed, C = Purina Dog Chow Senior, and D = Eukanuba Senior Maintenance) for a 6-month testing period. Blood chemistry, microalbuminuria, and dual x-ray absorptiometry were done to evaluate changes in renal parameters and body composition over time. At the end of the 6 months, blood creatinine did not differ among dietary treatments, although dogs fed food A had lower BUN levels and BUN-creatinine ratios when compared with those fed the 3 commercial diets. Body weight and body fat increased in dogs fed food B, while foods A, C, and D maintained body fat. Dogs fed foods B and D lost lean muscle. The experimental food contained less protein and lower concentrations of phosphorus than the 3 commercial diets. Reducing the dietary protein concentration may slow renal decline by reducing negative effects of increased protein metabolism. Some loss of lean muscle could potentially be prevented by providing additional essential amino acids that promote protein synthesis and prevent protein degradation.

The effect of dietary protein on body composition and renal function in geriatric dogs. Frantz NZ, Yamka RM, Friesen KG. Intl J Appl Res Vet Med 5:57-64, 2007.