Prevalence of Ear Disease in Dogs Undergoing Multidetector Thin‐slice Computed Tomography of the Head

Abstract

Previous reports describing the prevalence of ear diseases in dogs have primarily been based on dogs presenting with clinical signs of disease. The prevalence of subclinical ear disease remains unknown. The purpose of this cross-sectional retrospective study was to describe the prevalence of lesions consistent with middle and external ear disease in dogs presented for multidetector computed tomography (CT) of the head and/or cranial cervical spine at our hospital during the period of July 2011 and August 2013. For each included dog, data recorded were signalment, CT findings, diagnosis, and treatment. A total of 199 dogs met inclusion criteria. Nineteen dogs (9.5%) were referred for evaluation of suspected ear disease and 27 dogs (13.5%) had histories or physical examination findings consistent with otitis externa. A total of 163 dogs (81.9%) had CT lesions consistent with external ear disease (i.e. ear canal mineralization, external canal thickening, and/or narrowing of the external canal). Thirty-nine dogs (19.5%) had CT lesions consistent with middle ear disease (i.e. soft tissue attenuating/fluid material in the tympanic bullae, bulla wall thickening or lysis, and/or periosteal proliferation of the temporal bone). Findings from this study indicated that the prevalence of external and middle ear disease in dogs could be higher than that previously reported.

Comparison Between Computed Tomographic Characteristics of the Middle Ear in Nonbrachycephalic and Brachycephalic Dogs With Obstructive Airway Syndrome

“…Although it is impossible to be sure of the constitution of the bulla contents without myringotomy, examination and analysis of the fluid/tissue, it seems likely that the material observed in the middle ear of brachycephalic dogs represents noninflammatory fluid as none of the dogs had clinical signs of otitis media or other imaging findings suggesting inflammation. In other publications, the incidence of dogs with subclinical otitis media varied from 12.5% to 41%, with a higher prevalence in brachycephalic dogs (Cavalier King Charles spaniels, Bulldogs, and Boxers), mainly reported with MRI . Our results support the predisposition of brachycephalic dogs to having subclinical middle ear disease.…”

“…C omputed tomography (CT) and magnetic resonance imaging (MRI) examinations of the head in dogs and cats frequently detect subclinical tympanic bulla lesions, with a reported prevalence up to 41% in dogs . Computed tomography and MRI have been previously established as accurate methods for identification of fluid within the canine tympanic bulla .…”

“…Although the CT anatomy of the dog ear has previously been reported, there is no published information on the dimensions of the tympanic bulla in dogs, and whether this is affected by head shape . Subclinical middle ear disease or otitis media have been defined in previous reports as the incidental presence of fluid or material in the middle ear with no bony abnormalities or concurrent clinical signs . Pathological changes due to middle ear disease in CT have been described as attenuating material in the tympanic bullae, bulla wall thickening/lysis, and/or periosteal proliferation on the temporal bone .…”

Computed tomographic findings in 205 dogs with clinical signs compatible with middle ear disease: a retrospective study

“…The prevalence of middle ear CT lesions in the current study was 32.9%. This is higher than a previous study where the prevalence of otitis media was reported as 19.5% in dogs presented for CT scan of the head or cervical spine . However, comparison should be considered cautiously because the reasons for referring cases for CT can vary amongst referring veterinarians.…”

“…The availability, cost, shorter scanning time and the maximized visualization of bony structures make high‐resolution CT the method of choice in the imaging of the middle ear in humans . Computed tomography has been proposed as an alternative to evaluate middle ear structures in animals . This noninvasive diagnostic technique allows visualization of anatomic structures in cross‐section, while avoiding the superimposition of ear structures, which occurs on radiographs.…”