Evaluation of mesenteric lymphangiography and thoracic duct ligation in cats with chylothorax: 19 cases (1987-1992).

Mesenteric lymphangiography and thoracic duct ligation were performed on 19 cats with chylothorax between 1987 to 1992. Chylothorax was diagnosed on the basis of detection of chylomicrons in the pleural effusion or determination of a cholesterol concentration:triglyceride concentration ratio of < 1 in the pleural fluid. Preoperative medical treatment consisted of thoracentesis (19 of 19 cats) and feeding a fat-restricted diet (14 of 19 cats). Positive-contrast mesenteric lymphangiography was performed before thoracic duct ligation to identify an underlying cause for the effusion. Lymphangiectasia was diagnosed by use of radiography in 17 cats, none of which had evidence of a thoracic duct rupture. Thoracic duct ligation was performed via an incision made through the left 10th intercostal space. Lymphangiography was repeated immediately after ligation of the thoracic duct to document occlusion of all branches. Follow-up monitoring was done for 12 to 47 months (median, 28 months) and consisted of physical examination, evaluation for clinical signs related to pleural effusion, and thoracic radiography. Ten of 19 (53%) cats had complete resolution of pleural effusion. Nonchylous effusion, localized in the right hemithorax, was detected in 1 cat 2 months after thoracic duct ligation, but resolved after thoracotomy, breakdown of thoracic adhesions, and expansion of the right cranial lung lobe. Chylous effusion resolved 3 to 7 days (mean, 5.4 days) after surgery in the 10 cats that survived > 12 months after surgery. Four cats died between 2 and 13 days after thoracic duct ligation, but pleural effusion had resolved in 3 of these 4 cats at the time of death.(ABSTRACT TRUNCATED AT 250 WORDS)