This technique involves the removal of most of the sac surrounding the heart (pericardium) and is performed for the treatment of multiple conditions including chylothorax, conditions leading to the accumulation of fluid (pericardial effusion) within the pericardium e.g. heart base tumors, and other conditions leading to constriction of the pericardium around the heart. Traditionally this technique is performed via a right lateral intercostal thoracotomy necessitating opening of the chest and spreading of the ribs. Using thoracoscopic instrumentation this procedure can be performed quickly, easily and safely with the use of the ligasure vessel sealing device to prevent hemhorrage in thickened and inflamed pericardium. Animals undergoing thoracoscopic surgery recover quicker and in our opinion remain more comfortable throughout the recovery period.