The outcome and complications associated with thoracic duct ligation combined with partial pericardiectomy in 14 dogs with idiopathic chylothorax were investigated retrospectively. Nine of the dogs were treated in the uk and five in Italy. All of them were reassessed clinically four weeks after surgery and the respiratory function and any pleural fluid accumulation were evaluated; they were followed up by telephone contact for at least six months. Eleven of the dogs were clinically normal and had no radiographic signs of pleural effusion when reassessed after four weeks. Two showed radiographic signs of a minor accumulation of pleural fluid but were clinically normal; when reassessed after three months they showed similar radiographic signs and clinical findings; but after four months there was no evidence of pleural effusion. One dog had a major complication that required a second surgical intervention.