Intraoperative Application of Indocyanine Green in Canine Metastatic Intestinal Adenocarcinoma

A 12–year–old castrated male mongrel was presented with an intestinal mass, weight loss, and hematochezia. Diagnostic imaging identified a soft tissue mass in the ileum and two enlarged intra–abdominal lymph nodes. Surgical resection was performed with intraoperative guidance using near–infrared fluorescence (NIRF) imaging and indocyanine green (ICG). The tumor exhibited reduced fluorescence compared to the surrounding intestine, enabling negative contrast–based visualization of the resection boundary and preservation of the ileocecal valve. Submucosal injection of ICG intraoperatively allowed clear visualization of lymphatic drainage and identification of a fluorescent sentinel lymph node (SLN). Histopathological examination confirmed complete excision of an invasive adenocarcinoma with tumor–free margins. The fluorescent lymph node was metastatic, while the non–fluorescent enlarged node was benign adipose tissue. The patient recovered uneventfully, with no recurrence or metastasis observed at the one–year follow–up. This case demonstrates the clinical utility of ICG–NIRF imaging in guiding margin assessment and SLN mapping during intestinal tumor surgery in a dog. The approach facilitated more accurate staging and conservative resection, potentially reducing surgical morbidity. This case report describes the first documented veterinary case of ICG–NIRF–guided resection and SLN mapping for canine intestinal adenocarcinoma.