Unilateral congenital aneurysm of the jugular, linguofacial, and maxillary veins in a dog.

: A 5-month-old female Gordon Setter was examined because of a soft, fluctuant, subcutaneous swelling in the right submandibular region. Clinical problems were not associated with the mass. Cytologic examination and blood gas analysis of an aspirate from the mass confirmed its contents to be venous blood. Venous angiography delineated a fusiform dilatation of the right jugular, maxillary, and linguofacial veins, with no evidence of obstruction or anomalous venous return to the heart. The dilated segments were surgically excised, and the tissue was submitted for histologic examination. The clinical, radiographic, and histologic features of this lesion supported the diagnosis of congenital venous aneurysm.