Computed tomography can differentiate vaginal-origin from uterine-origin lesions in bitches

OBJECTIVE To investigate typical computed tomography (CT) features for the differentiation of vaginal from the uterine origin in dogs. ANIMALS 7 healthy Beagles in the prospective study and 5 bitches in the retrospective study. PROCEDURES In the prospective study, dual-phase CT images were obtained from sexually intact female Beagles (n = 7) during anestrus and estrus. On the CT images, the vagina and uterine horns, body, and cervix were assessed for diameter, attenuation, and contrast enhancement pattern. In the retrospective study, CT features of large vaginal lesions (leiomyoma, leiomyosarcoma, adenocarcinoma, hematocolpos, and Gartner’s duct cyst) were assessed in 5 bitches. RESULTS In normal bitches, the cervix was thicker with strong central enhancement compared to the uterus and vagina. The uterine artery, which enters the mesometrium at the level of the cervix, was clearly visualized and assisted in iden-tifying the cervix. In bitches with large vaginal masses, uterine arteries were displaced by the lesions and could not be used to locate the cervix. In 4/5 dogs with vaginal masses, identification of the cervix allowed the determination of the organ of origin. In 1 dog with adenocarcinoma, CT vaginography was additionally required for determining the origin of mass. CLINICAL RELEVANCE Results from this study indicate that the cervix, recognized in CT as focal thickening of the uterus with central enhancement, may be used as a landmark for the differentiation between the uterus and vagina in bitches.