title: Prevalence and characterization of small tympanic bone spicules and drumstick-like hyperostotic tympanic bone spicules in the middle ear cavity of dogs.
abstract: Rounded, sessile, hyperattenuating structures detected in computed tomography (CT) studies of canine tympanic bullae have been termed "otoliths." These have been proposed to represent dystrophic mineralizations or heterotopic bone formations in the middle ear that are potentially related to chronic otitis media. Aims of the current study were to describe the prevalence, macroscopic, and histological features of structures consistent with "otoliths" in the canine tympanic cavity. Tympanic bullae from 50 routinely necropsied dogs and 139 retrospectively retrieved CT scans of canine clinical cases were examined. Small tympanic bone spicules with pointed or clubbed tips essentially arising from the free margin of the septum bullae were bilaterally present in the tympanic cavities of all 50 of the necropsied dogs. In 48% of the dogs, "otolith"-like CT-detectable bone spicules carrying drumstick-like hyperostoses that were 1-6 mm in diameter were also present. In the retrospective survey of bulla CT scans of 139 cases, the prevalence of hyperostotic tympanic bone spicules (HTBS) was 20%. Findings from the current study indicated that the presence of small tympanic bone spicules in adult dogs is most likely due to physiological bone growth in the septum bullae and that HTBS represent osseous proliferations of small tympanic bone spicules. However, the factors inducing formation of hyperostotic spicules from small tympanic bone spicules remain unknown. The high prevalence of HTBS displaying a similar appearance in bulla CT scans in dogs suggests that these spicules should be included in a differential diagnosis list for "otoliths."
authors.affiliation: Department of Clinical Science and Services, Royal Veterinary College, University of London, UK.
authors.forename: Birgit
authors.initials: B
authors.lastname: Parzefall
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rieger
authors.forename: Holger A
authors.initials: HA
authors.lastname: Volk
authors.forename: Johann
authors.initials: J
authors.lastname: Maierl
authors.forename: Andreas
authors.initials: A
authors.lastname: Brühschwein
authors.forename: Andreas
authors.initials: A
authors.lastname: Blutke
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D002137:Calculi / Q000453:epidemiology / Q000662:veterinary; D004283:Dog Diseases / Q000453:epidemiology*; D004285:Dogs; D004427:Ear Diseases / Q000453:epidemiology / Q000662:veterinary*; D004432:Ear, Middle / Q000000981:diagnostic imaging; D005260:Female; D015576:Hyperostosis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000662:veterinary*; D008297:Male; D054850:Osteophyte / Q000453:epidemiology / Q000662:veterinary; D010033:Otitis Media / Q000453:epidemiology / Q000662:veterinary; D015995:Prevalence; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000662:veterinary; D014463:Ultrasonography
keywords: bone spicule CT; bulla tympanica; dog; otolith