Conformational risk factors of brachycephalic obstructive airway syndrome (BOAS) in pugs, French bulldogs, and bulldogs
Journal
PLoS ONE
Journal Volume
12
Journal Issue
8
Date Issued
2017
Author(s)
Troconis, Eileen L.
Kalmar, Lajos
Price, David J.
Wright, Hattie E.
Adams, Vicki J.
Sargan, David R.
Ladlow, Jane F.
DOI
POLNC
Abstract
Extremely brachycephalic, or short-muzzled, dog breeds such as pugs, French bulldogs, and bulldogs are prone to the conformation-related respiratory disorder—brachycephalic obstructive airway syndrome (BOAS). Affected dogs present with a wide range of clinical signs from snoring and exercise intolerance, to life-threatening events such as syncope. In this study, conformational risk factors for BOAS that could potentially aid in breeding away from BOAS were sought. Six hundred and four pugs, French bulldogs, and bulldogs were included in the study. Soft tape measurements of the head and body were used and the inter-observer reproducibility was evaluated. Breed-specific models were developed to assess the associations between the conformational factors and BOAS status based on functional grading. The models were further validated by means of a BOAS index, which is an objective measurement of respiratory function using whole-body barometric plethysmography. The final models have good predictive power for discriminating BOAS (-) and BOAS (+) phenotypes indicated by the area under the curve values of >80% on the receiver operating curves. When other factors were controlled, stenotic nostrils were associated with BOAS in all three breeds; pugs and bulldogs with higher body condition scores (BCS) had a higher risk of developing BOAS. Among the standardized conformational measurements (i.e. craniofacial ratio (CFR), eye width ratio (EWR), skull index (SI), neck girth ratio (NGR), and neck length ratio (NLR)), for pugs EWR and SI, for French bulldogs NGR and NLR, and for bulldogs SI and NGR showed significant associations with BOAS status. However, the NGR in bulldogs was the only significant predictor that also had satisfactory inter-observer reproducibility. A NGR higher than 0.71 in male bulldogs was predictive of BOAS with approximately 70% sensitivity and specificity. In conclusion, stenotic nostrils, BCS, and NGR were found to be valid, easily applicable predictors for BOAS (+). © 2017 Liu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Subjects
Article; body constitution; body plethysmography; brachycephalic obstructive airway syndrome; bulldog; controlled study; dog breed; female; French bulldog; male; measurement; morphology; nonhuman; nose malformation; pug; respiratory function; respiratory tract disease; risk factor; sensitivity and specificity; airway obstruction; animal; breeding; Craniosynostoses; dog; Dog Diseases; genetics; observer variation; regression analysis; reproducibility; species difference; syndrome; veterinary; Airway Obstruction; Animals; Breeding; Craniosynostoses; Dog Diseases; Dogs; Female; Male; Observer Variation; Plethysmography, Whole Body; Regression Analysis; Reproducibility of Results; Risk Factors; Species Specificity; Syndrome
Publisher
Public Library of Science
Type
journal article