What is known
Veterinary nutritional guidance and canine feeding research strongly support the biological necessity of meeting defined nutrient requirements and avoiding both deficiency and inappropriate excess. Controlled canine research demonstrates clinically important consequences when key nutrient supply is inadequate. Some alternative complete diets have maintained measured health indices in prospective studies, illustrating that diet category alone is not a reliable proxy for nutritional adequacy or superiority; those studies do not establish superior longevity.