Quantitative assessment of preoperative and postoperative brachycephalic airway obstruction syndrome surgery using clinical grading questionnaires and 6-minute walk test in French bulldogs

Brachycephalic airway obstructive syndrome (BAOS) is an anatomical abnormality of the upper airway commonly found in brachycephalic breeds, leading to clinical signs and physical capacity impairment. The degree of stenotic nares was reported to be related to BAOS severity in French bulldogs. This study aimed to compare clinical signs and physical capacity in French bulldogs before and after BAOS surgery using modified Roedler questionnaires and a 6-minute walk test (6-MWT). Twenty-seven French bulldogs were enrolled in this study (non-BAOS control (n=7), non-severe stenotic nares BAOS dogs (n=8), and severe stenotic nares BAOS dogs (n=12). BAOS surgery included staphylectomy using bipolar sealing device and vertical wedge alarplasty in all BAOS dogs. The non-severe and severe stenotic nares BAOS dogs before surgery had significantly higher overall BAOS severity scores assessed by owners using the questionnaire compared to the control dogs (vs 3(3.0-3.0) score, p<0.005) and their postoperative scores (17.5(15.25-19.0) vs 4.0(2.25- 6.0) score; p=0.002 and 15.5(14.0-19.75) vs 6.0(5.0-6.0) score; p=0.01, respectively). The postoperative 6-MWT distances significantly increased in non-severe and severe stenotic nares BAOS dogs when compared with their preoperative walk distances (500.6±12.67 vs 408.5±15.25 meters; p=0.0003 and 509.8±9.16 vs 403.5±13.86 meters; p=0.0001, respectively). The 6-MWT distances did not show significant differences between non-severe and severe stenotic nares BAOS dogs both before and after surgery (p>0.05). However, the severe stenotic nares BAOS French bulldogs at resting state had significantly higher preoperative compared to postoperative heart rate (132±2.23 vs 120±2.17; p=0.0002) and respiratory rate (59.67±5.98 vs 42.0±4.45; p=0.003). Pain score after surgery was minimal, and no respiratory complications were found immediately after surgery and 4 weeks postoperatively. There were marked improvements in respiratory clinical grades and overall questionnaire scores after surgery in both BAOS groups. Walk distances significantly increased in both BAOS groups after surgery and were similar to the control dogs (p>0.05). In conclusion, short-term postoperative surgical outcomes and physical capacity were excellent in French bulldogs with and without severe stenotic nares assessed by owner’s questionnaire scoring and 6-MWT in clinical settings. A quantitative assessment using 6-MWT as a noninvasive test was well-tolerated and feasible for monitoring exercise tolerance before and after BAOS treatment.