LAUSR

OBJECTIVE To document outcomes of thoracoscopic treatment of idiopathic chylothorax (IC) in dogs with and without constrictive pericardial physiology (CPP) and evaluate patterns of chyle flow redistribution after thoracic duct ligation (TDL). ANIMALS 26 client-owned dogs. PROCEDURES In this prospective cohort study, echocardiography and cardiac catheterization were performed to document CPP in dogs with IC. Thoracoscopic TDL with pericardiectomy was performed if CPP was present (TDL/P group). Dogs without evidence of CPP underwent thoracoscopic TDL alone (TDL group). Dogs underwent preoperative, immediate postoperative, and 3-month postoperative CT lymphangiography studies when possible. Perioperative morbidity, resolution and late recurrence rates, and long-term outcome were recorded. RESULTS 17 dogs underwent TDL, and 9 underwent TDL/P. Twenty-five of 26 (96%) survived the perioperative period. One dog died from ventricular fibrillation during pericardiectomy. Resolution rates for TDL and TDL/P were 94% and 88%, respectively (P = .55), with 1 late recurrence occurring in the TDL group in a median follow-up of 25 months (range, 4 to 60 months). On 3-month postoperative CT lymphangiography studies, ongoing chyle flow past the ligation site was demonstrated in 5 of 17 dogs, of which 1 dog developed recurrence at 13 months postoperatively. In 15 of 17 dogs, chylous redistribution after TDL was principally by retrograde flow to the lumbar lymphatic plexus. CLINICAL RELEVANCE In dogs without evidence of CPP, TDL alone was associated with a very good prognosis for treatment of IC. In the absence of CPP, the additional benefit of pericardiectomy in the treatment of IC is questionable.