Partial Venous Inflow Occlusion under Mild Hypothermia for Membranectomy in a Dog with Cor Triatriatum Dexter

SIMPLE SUMMARY: This report describes a case of cor triatriatum dexter in which a persistent embryonic membrane within the right atrium obstructed venous blood inflow from the caudal vena cava. Several treatment options for dogs presenting with clinical signs related to cor triatriatum dexter, such as interventional approaches, cardiopulmonary bypass, or venous inflow occlusion, have been published in the veterinary literature. Each method has advantages and disadvantages; however, membranectomy via venous inflow occlusion is considered an effective and safe treatment compared with other methods, as it can be performed within a short period and reduces the risk of recurrence. To the best of our knowledge, this is the first case report documenting the surgical treatment of a cor triatriatum dexter in a dog using partial venous inflow occlusion under mild hypothermia. ABSTRACT: Cor triatriatum dexter (CTD) is an uncommon congenital cardiac anomaly in dogs. This case report describes successful membranectomy for CTD via partial venous inflow occlusion under mild hypothermia in a dog. A 7-month-old intact male mixed-breed dog weighing 20.5 kg presented with a history of abdominal distention, lethargy, and anorexia. Clinical examination, radiography, echocardiography, microbubble testing, and computed tomography revealed a remnant right atrium membrane obscuring the venous blood inflow from the vena cava. Considering the potential risk of re-stenosis following interventional treatment, curative resection involving surgical membranectomy via venous inflow occlusion was performed. By performing partial venous inflow occlusion under mild hypothermia (34.5 °C), sufficient time was obtained to explore the defect and resect the remnant membrane. The dog recovered without any complications, and the clinical signs were relieved. This case illustrates that partial venous inflow occlusion under mild hypothermia is feasible for achieving curative resection of cor triatriatum dexter in dogs.