Prevalence and characterization of middle ear effusion in 55 brachycephalic dogs

Multiple, breeding-related malformations of the skull of brachycephalic dogs are well-known. Whereas the eye-catching deformities of the nose that lead to dramatic respiratory problems are obvious, changes of the middle ear are often an incidental finding on CT examinations and usually clinically inapparent. The objectives of this work were to investigate the prevalence and characteristics of middle ear effusion in brachycephalic dog breeds presented for multilevel surgery of upper airway obstructions.

Brachycephalic dogs with incidental middle ear effusion detected on CT scans obtained prior to surgical treatment of brachycephalic airway syndrome were prospectively enrolled. A perendoscopic tympanocentesis followed by macroscopic description, microscopic cytology and bacteriological analysis of the fluid was performed.

Prevalence of middle ear effusion in all dogs presented to the department during the study period was 55/170 (32 %) in 86 middle ears. The only breeds suffering from MEE were French Bulldogs (FB) with a prevalence of 35/66 (53 %) and Pugs with a prevalence of 20/79 (25 %). Tympanocentesis was performed in 80 ears. In the majority of cases the effusion was either mucoid or serous, with a honey-like or ochre colour.Bacteriology was available for 76 ears and tested positive in 34 (45 %) cases. Cytology was performed in 73 ears and revealed all effusions to contain inflammatory cells with a high concentration in 23 (31.5 %) cases.

Brachycephalic dogs presented for surgical treatment of brachycephalic airway syndrome have a high prevalence of incidental middle ear effusions. Cytological findings differ from previously reported analyses of effusions in Cavalier King Charles spaniels with clinical symptoms of primary secretory otitis media, where usually cell-free effusions are found. A study comparing effusions of brachycephalic dogs with vestibular disease to those found as an incidental condition is warranted.