¹Bursa Uludağ University, Faculty of Veterinary Medicine, Department of Internal Medicine, TR-16059 Bursa - TÜRKİYE DOI : 10.9775/kvfd.2026.37248 Myxomatous mitral valve disease (MMVD) is associated with progressive structural cardiac remodeling and systemic inflammatory and metabolic alterations. This study aimed to develop and preliminarily evaluate Canine Inflammatory-Metabolic Risk Index (CIMRI) as a composite biomarker, assess its differences across ACVIM stages and associations with echocardiographic indices, and explore its ability to discriminate dogs with current or previous congestive heart failure (CHF) from those without CHF. Fifty client-owned dogs were retrospectively enrolled and equally distributed across five disease stages. CIMRI was calculated using routinely available laboratory variables reflecting immune response, metabolic balance, and electrolyte status, normalized to total protein concentration. Associations with echocardiographic variables were assessed using Spearman"s correlation analysis, and discriminatory performance was evaluated by receiver operating characteristic (ROC) analysis. CIMRI differed significantly across ACVIM stages, with the highest values observed in Stage D (P<0.001), and correlated positively with LA/Ao (ρ = 0.631, P<0.001) and LVIDdN (ρ = 0.561, P<0.01). ROC analysis yielded an AUC of 0.929 (95% CI: 0.837-1.000) for discriminating dogs with current or previous CHF (Stages C-D) from those without current or previous CHF (Stages A-B2). At the optimal cut-off of >5.8, sensitivity and specificity were 95.0% and 90.0%, respectively. These findings support further evaluation of CIMRI as an exploratory composite biomarker associated with MMVD severity and CHF status in larger independent, prospective, and longitudinal populations. Keywords : Canine, Composite Index, Echocardiography, Inflammatory-metabolic index, Myxomatous mitral valve disease