Real-time elastography is a recently introduced ultrasound technique allowing the investigation of elastic properties of tissues. A diagnostic accuracy study was conducted to test the performance of this technique in the assessment of subcutaneous lesions in dogs. Fifty-two dogs were prospectively included in the preliminary study (34 malignant and 18 benign lesions). B-mode ultrasound was performed assessing the shape, margins, heterogeneity, and echotexture of the lesions. On elastosonography, assessment of the percentage of softness/hardness was recorded. A qualitative assessment was performed according to the Tsukuba elasticity score with a 1-5 score, representing the increased percentage of high stiffness areas. Results were compared with cytology/histopathology of the lesions. Receiver Operating Curves of the overall diagnostic sensitivity and specificity were obtained. Fisher’s exact test and Pearsons’s Chi-squared test estimated the relationship between the B-mode appearance of the lesions and final diagnosis. A hardness cutoff of 50.25% was identified between lesions, with malignant neoplasms having higher percentages. A 100% specificity and 89% sensitivity for correctly detecting the nature of the lesion on elastosonography was established. Qualitative assessment of the Tsukuba elasticity score established 1.5 as the cutoff between elastograms of lipomatous and malignant lesions, with 100% sensitivity and 61% specificity in differentiating them. Real-time elastosonography is a novel, noninvasive, and accurate technique for differentiating malignant from benign lipomatous lesions in dogs. This method could be considered as a complementary tool with additional diagnostic value for routine invasive procedures, such as fine needle aspirates.