Table 1.
Inclusion and exclusion criteria for breaths accepted in the mid-expiratory flow rate analysis.
Fig 1.
Line colours corresponding to the following measurements: (a) Blue: body length, (b) Orange: body height, (c) Pink: neck girth, (d) Yellow: chest girth, (e) Green: tail length.
Table 2.
Conformational measurements taken through soft tape and photographic measurements.
Fig 2.
Photographic conformational measurements.
(A) Frontal plane (FP) photographs were taken with the camera facing directly from rostral to caudal, with the subject looking directly at the camera lens. Measurements include ICD (pink line) and SW (green line). (B) Dorsal plane (DP) photographs were taken with the camera looking down at the subject from a bird’s eye view; dorsally to ventrally and perpendicular to the frontal plane. Measurements include SW (green line) and SL (yellow). (C) Sagittal plane (SP) photographs were taken as a side-on view, directly lateral to the subject and parallel to the midline sagittal plane. Measurements include MzL (red line) and CrL (blue line).
Fig 3.
The BOAS grade distribution of Boston Terriers in the sample population.
Percentages compared to that of graded of Bulldogs and French Bulldogs in the previous study by Liu et al. [1].
Fig 4.
Mean mid-expiratory flow rates recorded at each quartile of the expiratory breath.
Considered for three sample populations: 1. Control dogs, 2. BOAS Grade 0 Boston Terriers (BTs) and 3. BOAS Grade 1–3 Boston Terriers (BTs). Flow rates have been normalised to body weight (kg). Error bars displayed and 95% confidence intervals represented by dashed lines.
Fig 5.
Example whole-body barometric respiratory flow traces from the three sample populations.
(A) Control dog. (B) Grade 0 Boston Terrier. (C) Grade 2 Boston Terrier.
Fig 6.
Boxplots of conformational measurements in Grade 0 versus Grade 1–3 Boston Terriers.
Neck to chest girth ratio (p = 0.039), tail length (p = 0.052), skull index (p = 0.0002) and craniofacial ratio (p<0.0001).
Fig 7.
The percentage of BOAS Grade 0 versus BOAS Grade 1–3 Boston Terriers across different subjective conformation variables.
Nostril stenosis (p = 0.002), scleral show (p = 0.04) and body condition score (p = 0.15).
Fig 8.
Multiple logistic regression analysis of selected signalment and conformational factors.
Six variables included in analysis (nostril stenosis, scleral show, NGR, tail length, SI and CFR) with classification cut-off value at 0.5. Boxplot displaying the probability of the model predicting observed BOAS Grade 0 (0) and BOAS Grade 1–3 (1). Receiver operating characteristic (ROC) curve of the model with area under curve of 0.868 (Std. error: 0.0411, 95% CI: 0.788–0.949, p<0.0001).
Fig 9.
Comparative illustration of the conformation of Boston Terriers with lower and higher BOAS risk.
(A) Lower risk conformation characteristics: longer muzzle with narrower skull, no abnormal scleral show, open nostrils, and proportionally slimmer neck. (B) Higher risk conformation characteristics: more extreme facial hypoplasia with shortened muzzle and wider skull, abnormal scleral show, stenotic nostrils, and proportionally thicker neck.