Taurine-Deficiency versus Diet-Associated Dilated Cardiomyopathy in Dogs: A Mechanistic and Comparative Critical Review

Taurine-deficiency dilated cardiomyopathy (TD-DCM) is a well-characterized, reversible myocardial disorder in dogs, mechanistically driven by impaired sulfur amino acid (SAA) metabolism, taurine depletion, and subsequent disruption of calcium homeostasis, mitochondrial function and antioxidant capacity. In contrast, diet-associated dilated cardiomyopathy (da-DCM) is a multifactorial syndrome reported in dogs consuming certain commercial diets, many of which are high in legumes or labelled as “grain-free”, frequently occurring in the absence of taurine deficiency. This review provides an advanced mechanistic comparison between TD-DCM and da-DCM, emphasizing biochemical, metabolic, mitochondrial, genetic, microbiome-mediated and nutrient digestibility pathways. The analysis highlights both overlapping and diverging mechanisms, critiques the robustness of current evidences, and outlines the limitations in FDA reports. A modern framework is proposed that unifies taurine-dependent and taurine-independent pathways, focusing on SAA bioavailability, anti-nutritional factors, bile acid turnover, mitochondrial energy failure and altered cardiac substrate metabolism. Improved diet formulation, metabolomic profiling and long term studies are essential for clarifying causality and refining clinical management.