Canine mammary neoplasms are naturally occurring non-homogenous group of tumours with many resemblances to human breast cancer. In female dogs mammary tumours are of great clinical relevance due to the high prevalence and mortality rate, which varies according to the histopathological classification and clinical stage. The aim of the study was to compare the ultrasonographic features of the normal mammary gland with benign and malignant mammary neoplasms in dogs, through assessed by B-mode and Doppler mode ultrasonography. Ultrasonographic examination of seven normal mammary glands along with six benign and 12 malignant mammary neoplasms were performed. Among the parameters evaluated by B-Mode ultrasonography, significant differences were found (p < 0.01) in the tumour margin and invasiveness of neoplasms, where malignant tumours were invasive with uncircumscribed margin. Significant difference was also found in the presence of posterior acoustic enhancement (p<0.05) between benign and malignant mammary neoplasms. Elevated peak systolic velocity of blood flow within the tumour vessels in malignant mammary neoplasm was the only feature assessed with Doppler mode having significant difference.