Clinical Severity Score System in Dogs with Degenerative Mitral Valve Disease

BACKGROUND: Several risk factors already have been determined for dogs with degenerative mitral valve disease (DMVD). Risk factors often have been considered in isolation and have not always taken into account additional information provided by the history and physical examination (PE). HYPOTHESIS/OBJECTIVES: Data obtained from history and PE of dogs with DMVD provide prognostic information and can be used for risk stratification. ANIMALS: Client‐owned dogs (n = 244) with DMVD recruited from first opinion practice. METHODS: Prospective longitudinal follow‐up of dogs with DMVD. History and PE data were obtained at 6‐month intervals and analyzed with time‐dependent Cox models to derive relative risk of cardiac death. Independent hazard ratios were used to derive a clinical severity score (CSS), the prognostic value of which was evaluated by analyzing the median survival times for different risk groups and ROC analysis. Analysis of the progression of CSS over time also was undertaken. RESULTS: History of cough, exercise intolerance, decreased appetite, breathlessness (difficulty breathing) and syncope with PE findings of heart murmur intensity louder than III/VI and absence of respiratory sinus arrhythmia were independently associated with outcome and allowed development of the CSS. Clinical severity score distinguished groups of dogs with significantly different outcomes. CONCLUSIONS AND CLINICAL IMPORTANCE: Routinely obtained clinical findings allow risk stratification of dogs with DMVD. Results of ancillary diagnostic tests may be complementary to history and PE findings and always should be interpreted in conjunction with these findings.