Abstract
The lymphatic drainage pattern of normal canine mammary glands was investigated in an anatomical study using India ink, and the usefulness of three-dimensional computed tomographic analysis (3D-CT) with contrast media for visualization of sentinel lymph nodes was examined in a clinical setting.
In the anatomical study, the first and second mammary glands consistently drained into the ipsilateral axillary lymph nodes in all dogs. In two of three cases, the third mammary gland drained simultaneously into the ipsilateral axillary lymph nodes cranially and into the superficial inguinal lymph nodes caudally. In one of these two cases, the lymph drained into the contralateral inguinal lymph nodes via the pelvic lymphatic plexus. In the remaining case, the third mammary gland only drained caudally into the ipsilateral superficial inguinal lymph nodes. In five cases, the fourth mammary gland, and in two cases, the fifth mammary gland, usually drained into the ipsilateral superficial inguinal lymph nodes and medial iliac lymph nodes in the abdominal cavity. However, in one case, the fourth mammary gland drained into the contralateral inguinal lymph nodes via the pelvic lymphatic plexus, as also seen in the third mammary gland.
The CT analysis showed that the lymphatic pathways draining directly from the injection sites of small doses of contrast medium were quickly and sufficiently enhanced in the animals without any significant late adverse effects. In particular, topographic 3D-CT lymphography provided detailed anatomical information on individual lymphatic channels and nodes without overlaps with the surrounding structures.
Thus, visualization of lymph drainage using simple, noninvasive 3D-CT is useful for easy identification of the lymph drainage route and is necessary not only to determine the most appropriate surgical treatment of mammary tumors, but also to determine an accurate postsurgical prognosis.
