Vascularized lymph node transfer (VLNT) has become more wide-spread for surgical treatment of lymphedema. However, interaction between a transferred lymph node and the recipient lymphatic system in relieving lymphedema has not been identified. The aims of this study were to investigate anatomical changes in the lymphatic system in the forelimb of a canine after lymph node dissection and irradiation and to clarify the interaction between the transferred lymph node and recipient lymphatics.

Two adult female mongrel canines were used for this exploratory study. The unilateral axillary and lower neck node dissections were performed, and 15-Gy irradiation was applied on postoperative day three. After one year, a VLNT flap was harvested from the lower abdominal region and inset in the axilla with vascular anastomoses. The girth of each forelimb was determined with a tape measure at different time points. Indocyanine green fluorescence lymphography and lymphangiography were performed before and after each surgery to evaluate morphological changes in the lymphatics.

Both canines revealed identical changes in the lymphatic system but only one canine developed lymphedema. After lymph node dissection, a collateral lymphatic pathway formed a connection to the contralateral cervical node. After VLNT, an additional collateral pathway formed a connection to the internal mammary node via the transferred node in the axilla.

The findings suggest that the lymphatic system has a homing mechanism, which allows the severed lymphatic vessels to detect and connect to adjacent lymph nodes. VLNT may create new collateral pathways to relieve lymphedema.