Characterisation of Brachycephalic Obstructive Airway Syndrome in French Bulldogs Using Whole-Body Barometric Plethysmography

Abstract

Brachycephalic obstructive airway syndrome (BOAS) is an important health and welfare problem in several popular dog breeds. Whole-body barometric plethysmography (WBBP) is a non-invasive method that allows safe and repeated quantitative measurements of respiratory cycles on unsedated dogs. Here respiratory flow traces in French bulldogs from the pet population were characterised using WBBP, and a computational application was developed to recognise affected animals. Eighty-nine French bulldogs and twenty non-brachycephalic controls underwent WBBP testing. A respiratory functional grading system was used on each dog based on respiratory signs (i.e. respiratory noise, effort, etc.) before and after exercise. For development of an objective BOAS classifier, functional Grades 0 and I were considered to have insignificant clinical signs (termed here BOAS-) and Grades II and III to have significant signs (termed here BOAS+). A comparison between owner-perception of BOAS and functional grading revealed that 60 % of owners failed to recognise BOAS in dogs that graded BOAS+ in this study.WBBP flow traces were found to be significantly different between non-brachycephalic controls and Grade 0 French bulldogs; BOAS- and BOAS+ French bulldogs. A classifier was developed using quadratic discriminant analysis of the respiratory parameters to distinguish BOAS- and BOAS + French bulldogs, and a BOAS Index was calculated for each dog. A cut-off value of the BOAS Index was selected based on a receiver operating characteristic (ROC) curve. Sensitivity, specificity, positive predictive value, and negative predictive value of the classifier on the training group (n=69) were 0.97, 0.93, 0.95, and 0.97, respectively. The classifier was validated using a test group of French bulldogs (n=20) with an accuracy of 0.95. WBBP offers objective screening for the diagnosis of BOAS in French Bulldogs. The technique may be applied to other brachycephalic breeds affected by BOAS, and possibly to other respiratory disease in dogs.

Development and validation of a brachycephalic risk (BRisk) score to predict the risk of complications in dogs presenting for surgical treatment of brachycephalic obstructive airway syndrome

“…Although multiple planned procedures have not been previously identified as a risk factor in brachycephalic dogs, prolonged anesthetic time, which is highly correlated with multiple procedures, has been identified as a risk factor for postanesthetic complications in brachycephalics . Obese dogs are reported to be 1.9‐fold more likely than dogs with normal body condition to show signs of BOAS, and severity of respiratory noise has been found to correlate with degree of airway function compromise …”

Whole‐Body Barometric Plethysmography Characterizes Upper Airway Obstruction in 3 Brachycephalic Breeds of Dogs

“…Each dog was graded for functional severity of BOAS using a previously established 4‐point functional grading system (Table ) based on clinical evaluation before and after a 3‐minute exercise tolerance test (ETT) . BOAS functional Grade 0 dogs (asymptomatic, BOAS free) and Grade I dogs (mild BOAS, dog shows mild respiratory noise but exercise tolerance is unaffected) were considered clinically healthy for their breed.…”

“…Whole‐body barometric plethysmography (WBBP) is a non‐invasive technique of measuring respiratory function that has been validated and utilized in unrestrained unsedated experimental mice to characterize respiratory patterns during sleep and wakefulness . This technique has also been used in experimental and clinical studies using dogs and cats for pharmacological studies and respiratory disorders . Our previous study on French bulldogs showed that respiratory airflow characteristics obtained from WBBP are distinguishable between BOAS‐affected and clinically healthy French bulldogs .…”

The impact of tongue dimension on air volume in brachycephalic dogs

“…Although the large tongue of brachycephalic dogs is readily appreciable by oral examination, it has been noted uncommonly and inconsistently in the peer‐reviewed literature, and, when mentioned, it is typically unreferenced or cited as an earlier anecdotal observation . Possibly because of the lack of robust documentation, macroglossia is not listed as a feature of brachycephalism in many major veterinary texts, so awareness of it may be low in the veterinary profession .…”