Cystadenocarcinoma is regarded as a rare adenocarcinoma variant in animals. This work reports the case of an 8-year-old female Poodle dog with salivary gland cystadenocarcinoma with morphological characteristics similar to a hemangiosarcoma. Histopathological analysis showed a tumor mass with cystic formations containing a large amount of red blood cells. In order to distinguish these two entities, periodic acid Schiff (PAS) staining and immunohistochemical analysis were carried out with the use of cytokeratin AE1/AE3 (CK) and CD31-specific antibodies. Neoplastic cells were PAS-negative, CK-positive and CD31-negative confirming their epithelial origin. Based on the findings, the diagnosis of high grade cystadenocarcinoma was established.