Minimally invasive management of idiopathic chylothorax

Idiopathic chylothorax (IC) in dogs is a complex and incompletely understood disorder that results in the accumulation of chyle within the pleural space resulting in respiratory distress and in some cases, restrictive pleuritis. Many treatment modalities, both medical and surgical, have been proposed for management of IC. Medical therapy with benzopyrones, low fat diets and medium chain triglycerides with or without intermittent pleural drainage are often discussed but have generally not been highly successful and no large studies exist reporting encouraging results with non-surgical management. It is now generally accepted that IC represents a surgical disease in most cases.

Early reports of surgical management of IC in dogs were not always highly encouraging and generally focused on the outcomes of thoracic duct ligation (TDL). In dogs early statistics suggested that resolution could be expected in only 59% of cases after TDL. In cats the outcomes of TDL were even poorer with studies reporting resolution in only 20-53% of cases.

Research into improving outcomes of this challenging condition has always been hampered by its infrequent occurrence. However, in recent years despite this challenge, a much better understanding of the natural variation of the lymphatic drainage patterns in cats and dogs has occurred and improvements in diagnostic imaging techniques have enhanced our ability to accurately identify the lymphatic anatomy in an individual patient. This in turn has improved pre- and intraoperative decision-making for existing techniques as well as spurring the development of new techniques. Intraoperative use of contrast agents such as methylene blue as well as lymphangiographic techniques using intraoperative fluoroscopy or pre- operative percutaneous computed tomographic (CT) lymphangiography have been described. These modalities have enhanced surgeons ability to make sure that all branches of the thoracic duct are ligated. The most recent advance in this area is the use of near-infrared fluorescence imaging for detection of lymphatic channels in the medistinum. A recent report described its use in 11 dogs with idiopathic chylothorax.  [...]