Abnormal shape of the pterygoid bone in French bulldogs: Prevalence and implication for cross-sectional area.

Abstract

OBJECTIVE: Retrospective observation of computed tomographic images to describe an anatomical difference in the shape of the pterygoid bone in French bulldogs (FB) and determine its prevalence and effect on the cross-sectional area of the airway, in comparison with normal conformation in brachycephalic and mesocephalic dogs. ANIMALS AND PROCEDURE: Computed tomographic studies of FB and cocker spaniels (CS) that underwent examination of the head were reviewed. The shape and cross-sectional area of the pterygoid bone was recorded and compared between groups. RESULTS: Thirty-six CS and 34 FB were included. In 79.41% (27/34) of FB, there was an abnormal shape of the pterygoid bone in comparison with all 36 CS, which had a normal shape of the pterygoid bone. Only 20.58% (7/24) of FB had a normal shape. The cross-sectional area of the airway at the level of the pterygoid bone for FB was 88.78 mm. The area was larger in FB with normal shape (average: 95.70 mm, SD &#xb1; 15.98) than those with abnormal shape (average: 86.98 mm, SD &#xb1; 20.32), though this difference was not statistically significant (> 0.05). Cocker spaniels had a larger airway cross-sectional area than dogs in both FB groups, with a mean of 142.28 mm(&#xb1; 24.87) and< 0.05. CONCLUSION AND CLINICAL RELEVANCE: French bulldogs frequently have an abnormal conformation of the pterygoid bone. This study identified further anatomical factors that might contribute to upper-airway obstruction in brachycephalic dogs.