Relationship Between Nasopharyngeal Dimensions and Middle Ear Effusion in Brachycephalic Breeds: A Computed Tomographic Comparison of Pugs and French Bulldogs

Objective:
To evaluate if middle ear effusion is related to small nasopharyngeal airway dimensions in pugs and French bulldogs (FB) using CT imaging.

Study Design:
Prospective CT study.

Animals:
30 pugs and 30 FB with brachycephalic upper airway syndrome and no clinical signs of otitis media.

Methods:
The thickness of the soft palate and cross-sectional areas of the nasopharyngeal aperture at the opening of the auditory tube were measured and computed to each individual’s skull index before statistical comparison between breeds. The middle ear was assessed for effusion, mucosal contrast enhancement and signs of osteitis. Statistical dependence of middle ear pathology and nasopharyngeal dimensions were assessed with Spearman’s rank correlation tests.

Results:
Middle ear effusion was seen in 56.6% of FBs and 16.6% of pugs. Contrast lining of the tympanic bulla was seen in 41.6% of FBs and 5% in pugs. Pugs had a significantly smaller cross-sectional airway dimension (p<0.00) and a thinner soft palate (p<0.00) compared to FB. Correlations between nasopharyngeal aperture and the presence of tympanic bulla effusion (r=0.198) or contrast enhancement (r=0.199) were very weak. A weak dependence was also found when the thickness of the soft palate was correlated to middle ear effusion (0.324) and bulla contrast enhancement (0.270).

Conclusion:
FBs were much more commonly affected with middle ear pathology despite significantly greater nasopharyngeal airway dimensions compared to pugs. Correlations between nasopharyngeal airway dimensions and middle ear pathology could not be found in this prospective CT study.