SURGICAL APPROACH TO THE SENTINEL LYMPH NODE IN DOGS

Abstract

The sentinel lymph node (SLN) is defined as the first lymphatic filtration point to receive drainage flow from a primary neoplasm, thus constituting the initial site of a possible metastasis. Accurate identification of this lymph node, especially in dogs diagnosed with mast cell tumors and mammary carcinomas, is crucial in assessing the extent of the disease, estimating prognosis, and choosing the most appropriate therapeutic approach. Evidence indicates that lymphatic drainage pathways diverge from those predicted by classical regional anatomy, which limits the effectiveness of lymphadenectomies performed without specific mapping guidance. Therefore, modern methods such as preoperative planar lymphoscintigraphy, indocyanine green (ICG) fluorescence imaging, and the use of lymphatic dyes, such as patent blue, demonstrate high sensitivity for SLN localization and allow the detection of subclinical metastases, resulting in more precise staging and therapeutic planning. Targeted histopathological analysis of these lymph nodes provides additional parameters for risk stratification and indication of complementary therapies. Sentinel lymph node (SLN) mapping is recommended before or during the surgical procedure, since prior excision of the primary tumor can interfere with physiological lymphatic drainage patterns, compromising diagnostic accuracy. In short, SLN mapping and histopathological analysis increase the accuracy of tumor staging and allow the identification of occult metastases that would not be detected by palpation or evaluation of the anatomical regional lymph node. Furthermore, sentinel and/or regional lymphadenectomy presents a low rate of postoperative complications (Souza et al., 2023). It is concluded that the surgical approach to the sentinel lymph node using mechanisms such as vital dyes represents a promising strategy in veterinary oncology, contributing to more precise staging and improved prognosis for canine patients.