Table 1.
Functional grading system of brachycephalic obstructive airway syndrome (BOAS) based on respiratory signs before and after an exercise tolerance test (ETT).
Fig 1.
The chamber used for whole-body barometric plethysmography (WBBP) with a French bulldog undergoing the test.
A pole of the chamber pressure differential transducer is opened to the top of the chamber (C); two inlets (A and B) are connected to the front and back of the chamber in order to ventilate with a bias flow of room air (20 L/minute); an audio sensor is located on the top of the chamber (D); together with pneumotachograph screens (E).
Fig 2.
WBBP flow waveform illustration for a single respiratory cycle.
The flow cycle starts from inspiration (below the zero line of flow rate) then expiration (above the zero line of the flow rate).
Fig 3.
A flowchart of the study design.
WBBP = whole body barometric plethysmography; BOAS = brachycephalic obstructive airway syndrome; QDA = quadratic discriminant analysis; SD = standard deviation; Te/Ti = expiratory time/ inspiratory time; PEF/PIF = ratio of peak expiratory flow to peak inspiratory flow; MV/BW = minute volume / body weight.
Table 2.
Signalment (median [minimum-maximum]) and details of French bulldogs and non-brachycephalic controls.
Fig 4.
Representative WBBP flow waveforms for several study dogs.
(A) non-brachycephalic control dog; (B) BOAS- French bulldog; (C) BOAS+ French bulldog, respiratory cycle Type 1; (D) BOAS+ French bulldog, Type 2; (E) BOAS+ French bulldog, Type 3.
Fig 5.
Breaths plotted against three selected respiratory parameters.
FB = French bulldogs; PEF/PIF = peak expiratory flow rate/ peak inspiratory flow rate; MV/BW = minute ventilation/ body weight, ml/kg; Te/Ti = expiratory time/ inspiratory time. 20 representative breaths per dog.
Table 3.
Respiratory parameters measured by whole-body barometric plethysmography (WBBP).
Fig 6.
Classification performance of the BOAS Index.
(A) Distribution of the BOAS Index for the French bulldog training dataset; (B) Box plots of the BOAS Index for the French bulldog training dataset according to functional grade. Boxes present lines at median, upper and lower quartiles; between whiskers = 95% confidence interval; circles = outliers within the inner fence; stars = outliers within the outer fence.
Fig 7.
Receiver operating characteristic (ROC) curve of the BOAS Index for diagnosis of functional BOAS+ French bulldogs.
Bootstrapping was used to generate the associated 95% confidence intervals (area in blue) to delineate the expected range of screening performance. The black dot with whiskers (95% confidence interval) shows the position of the BOAS Index of 0.46 suggested as a cut off point for distinguishing functionally BOAS- and BOAS+ French bulldogs.
Table 4.
Optimized classification results using BOAS Index (cut-off point BOAS Index = 0.46) for training and test French bulldogs datasets.