VDR and vitamin D deficiency: In our study, serum cholecalciferol concentrations were the presence of vitamin D receptors (VDRs) and activating hydroxylases in ventricular cardiomyocytes suggests a direct involvement in myocardial physiology This significant reduction may reflect an impaired vitamin D status associated with DCM pathogenesis, suggesting a potential link between vitamin D deficiency and cardiomyocyte dysfunction in affected dogs.