Degenerative mitral valve disease accounts for more than 75% of all cardiac diseases in dogs, with left atrial enlargement (LAE) being the primary radiographic sign [1]. In this retrospective study, the radiographic measurements Vertebral Heart Size (VHS), Radiographic Left Atrial Dimension (RLAD), and Vertebral Left Atrial Size (VLAS) were compared for the detection of LAE on lateral thoracic radiographs, correlating them with the echocardiographic left atrium to aortic root ratio (LA/Ao). Two groups were ana-lyzed: Group A with 35 radiographs (without LAE) and Group B with 24 radiographs (with LAE), in which VHS, RLAD, VLAS, and their corresponding LA/Ao ratio values were measured. The optimal cut-off value for each variable to detect LAE was determined using Receiver Operating Characteristic (ROC) curve analysis, and the sensitivity, speci-ficity, and area under the curve (AUC) were reported. The correlation of the radiographic measurements with LA/Ao ratio was also assessed. Moderate to high correlations were observed between VHS, RLAD, and VLAS and LA/Ao ratio (r = 0.77, 0.65, and 0.68, respectively). The specificity of all three measures was the same (91%), while their sensitivities were also similar (75%, 71%, and 67%, respec-tively). The optimal cut-off values were determined to be 11.1v for VHS, 2v for RLAD, and 2.2v for VLAS. It was concluded that all three radiographic measurements have comparable speci-ficity and sensitivity for detecting LAE in dogs.