Application of Preoperative Transarterial Chemoembolization Before Hilar Liver Tumour Resection in a Dog.

BACKGROUND: Hilar hepatocellular tumours in dogs pose a significant surgical challenge due to their proximity to major hepatic vessels. Preoperative reduction of tumour volume and vascular involvement may enhance surgical feasibility and improve outcomes. OBJECTIVES: To describe the use of transarterial chemoembolization (TACE) as a neoadjuvant strategy for downsizing hilar hepatocellular masses in dogs, thereby enabling safe and effective surgical resection. METHODS: A 12-year-old spayed female Beagle presented with a 5.1 cm × 8.1 cm × 8.9 cm hepatic mass in the left medial lobe, with suspected invasion into the left lateral lobe at the hilus. Conventional TACE was performed using idarubicin-loaded ethiodized oil emulsions and gelatin sponge particles. Four weeks after TACE, computed tomography was performed to assess the tumour response, followed by surgical resection 2 weeks later. RESULTS: The dog experienced mild abdominal discomfort and transient liver enzyme elevation following TACE, consistent with post-embolization syndrome. Tumour volume decreased by 38%, providing adequate space for vascular dissection and enabling successful resection with clear surgical margins. The dog recovered without major complications, remained recurrence-free 22 months postoperatively, and was still alive at the time of manuscript submission. Cytology confirmed a hepatocellular origin, although histopathology was non-diagnostic due to diffuse necrosis. CONCLUSIONS: Preoperative TACE may be an effective neoadjuvant therapy for reducing tumour size and facilitating surgical access in dogs with large liver tumours. This approach may present a viable option for dogs with hepatocellular tumours initially considered difficult to resect due to vascular involvement.