Comparison of submaximal exercise test results and severity of brachycephalic obstructive airway syndrome in English bulldogs

Canine brachycephalic obstructive airway syndrome (BOAS) is a complex respiratory disease related to congenitally flattened facial and skull anatomy. BOAS causes respiratory distress, heat and exercise intolerance, and gastrointestinal signs. English bulldogs (EB) have a high prevalence of BOAS. Currently, the severity of BOAS signs in veterinary practice is assessed subjectively. To reduce BOAS in brachycephalic breeds, an objective and easy-to-use tool could help breeders select healthier animals. Exercise tests, such as the 6 min walk test (distance walked measured) or the 1000 m walk test (duration measured), could be used to assess the severity of BOAS, as exercise intolerance and impaired recovery are key features of BOAS. This study evaluated the severity of signs and anatomic components of BOAS in a group of prospectively recruited young adult EBs (n = 28) and investigated the correlations of the 6 min walk test or the 1000 m walk test with a veterinary assessment of BOAS severity, using an ordinal 4 level scale of respiratory signs. EBs with more severe BOAS walked a shorter distance, more slowly and their recovery from exercise took longer than those with only mild signs of BOAS. Control dogs of different breeds (n = 10) performed the exercise tests significantly better (i.e. longer distance, faster time and recovery) than EBs. Increases in body temperature during exercise were significantly higher in EBs than in controls. The results of this study support the use of exercise tests for objective evaluation of the severity of BOAS in EBs.