Minimally invasive lymph node removal in 18 dogs using near-infrared

Abstract

OBJECTIVE: To describe laparoscopic extirpation of iliosacral lymph nodes (ISLNs) in tumor-bearing dogs using near-infrared fluorescence (NIRF) guidance with indocyanine green (ICG), detailing the surgical technique and complications. STUDY DESIGN: Retrospective case series. ANIMAL POPULATION: A total of 18 client-owned dogs. METHODS: Medical records of dogs that underwent laparoscopic ISLN excision with NIRF-ICG guidance between July 2023 and January 2025 were reviewed. Collected data included tumor location and histotype, sentinel lymph node (SLN) identified on preoperative computed tomography (CT) lymphangiography, and number, size, and metastatic status of the excised ISLNs. Complications were classified as intra- or postoperative and graded using a modified Clavien-Dindo system. RESULTS: A total of 25 ISLNs were laparoscopically excised: 18 medial iliac, three internal iliac, and four sacral. All patients were positioned in lateral recumbency, and resected ISLNs were ipsilateral to the primary tumor and laparoscopic ports. Median laparoscopic dissection time was 12 min. Histopathology confirmed metastasis in 12/25 ISLN. Median size of the excised ISLN was 5 × 6 mm. Two dogs (11.1%) required conversion to open surgery: one due to LN capsular disruption and dye spread, and one due to a lack of ICG uptake. No postoperative complications were documented. CONCLUSION: Laparoscopic ISLN removal under NIRF-ICG using a standardized lateral recumbency approach is feasible and enables access to unilateral ISLN. Intraoperative fluorescence facilitates precise localization of target nodes, especially those of normal size or mildly enlarged, minimizing dissection-related damage. CLINICAL RELEVANCE: This technique supports accurate staging of various neoplasms in dogs. Further studies are warranted to refine indications and patient selection.