OBJECTIVE To compare duration of surgery, recurrence rate, and survival time between cats with idiopathic chylothorax treated with thoracic duct ligation (TDL) plus subphrenic pericardiectomy (SPC) and those treated with TDL, SPC, and cisterna chyli ablation (CCA). DESIGN Retrospective case series with nested cohort study. ANIMALS 22 client-owned cats surgically treated for idiopathic chylothorax from 2009 through 2014. PROCEDURES Patient and surgery data were collected from the medical records. Recurrence of chylothorax and survival time were assessed by medical record review and client interview. Comparisons were made between cats treated with TDL plus SPC (TDL-SPC group) and those treated with TDL, SPC, and CCA (TDL-SPC-CCA group). RESULTS 15 cats were treated with TDL plus SPC, and 7 were treated with TDL, SPC, and CCA. Median duration of surgery was significantly briefer for the TDL-SPC group (80 minutes; range, 55 to 175 minutes) than for the TDL-SPC-CCA group (125 minutes; range, 105 to 205 minutes). Five cats (2 in the TDL-SPC group and 3 in the TDL-SPC-CCA group) had persistent pleural effusion 4 weeks after surgery. Chylothorax recurred in 2 cats (1/group). Median survival time in the TDL-SPC group was 774 days (range, 3 to 2,844 days) and in the TDL-SPC-CCA group was 380 days (range, 11 to 815 days); these values did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE Addition of CCA to the surgical treatment approach for cats with idiopathic chylothorax was associated with a significantly longer duration of surgery with no better outcome than achieved with TDL plus SPC alone.