Abstract Objective—To investigate whether time-frequency and complexity analyses of heart murmurs can be used to differentiate physiologic murmurs from murmurs caused by aortic stenosis (AS) in Boxers. Animals—27 Boxers with murmurs. Procedures—Dogs were evaluated via auscultation and echocardiography. Analyses of time-frequency properties (TFPs; ie, maximal murmur frequency and duration of murmur frequency > 200 Hz) and correlation dimension (T₂) of murmurs were performed on phonocardiographic sound data. Time-frequency property and T₂ analyses of low-intensity murmurs in 16 dogs without AS were performed at 7 weeks and 12 months of age. Additionally, TFP and T₂ analyses were performed on data obtained from 11 adult AS-affected dogs with murmurs. Results—In dogs with low-intensity murmurs, TFP or T₂ values at 7 weeks and 12 months did not differ significantly. For differentiation of physiologic murmurs from murmurs caused by mild AS, duration of murmur frequency > 200 Hz was useful and the combination assessment of duration of frequency > 200 Hz and T₂ of the murmur had a sensitivity of 94% and a specificity of 82%. Maximal murmur frequency did not differentiate dogs with AS from those without AS. Conclusions and Clinical Relevance—Results suggested that assessment of the duration of murmur frequency > 200 Hz can be used to distinguish physiologic heart murmurs from murmurs caused by mild AS in Boxers. Combination of this analysis with T₂ analysis may be a useful complementary method for diagnostic assessment of cardiovascular function in dogs.