Isolated soy protein and casein were compared as protein sources in canine diets. Digestibility, plasma concentrations of amino acids and some biochemical variables in the plasma were measured in four adult dogs. Casein and soy protein were highly digestible with apparent digestibilities of crude protein between 85-90 percent. The plasma amino-grams were influenced by dietary proteins. Dogs fed the soy protein treatment had increased plasma concentrations of arginine, while the relationship between branched chain and aromatic amino acid was not influenced. The effects of dietary proteins on biochemical variables were weak, but plasma urea, triglycerides and phosphorus increased significantly after meal intake. The authors proposed that dietary amino acid should be taken into consideration especially in diets fed for clinical nutrition reasons. Soy protein may counteract some of the changes in the plasma aminogram which have been reported in dogs with hepatocellular degeneration.

Zentek, J. and R. Mischke. 1997. Soya and casein as dietary protein for dogs. J. Anim. Phys. And Anim. Nutr (Zeitschrift Fur Tierphysiologie Tierenahrung und Futter mittekunde) 77(3):139-148.