Clinical aspects of middle ear tympanokeratoma in dogs diagnosed through advanced imaging, otoendoscopy and histopathological evaluation.

Background: Canine aural cholesteatoma (more appropriately named tympanokeratoma) is an epidermoid cyst whose aetiopathogenesis remains poorly recognised in veterinary medicine. There are a few reports published, possibly because it may be underdiagnosed.

Objectives: To characterise the clinical aspects of dogs with tympanokeratoma, to describe the otoendoscopic, advanced imaging and histopathological findings of tympanokeratoma and to report the best approach to diagnose canine auricular tympanokeratoma in a retrospective study.

Material And Methods: Of 890 dogs with suspected tympanokeratoma and otitis media, 100 animals underwent advanced imaging and otoendoscopy at radiology and dermatology reference centres in Brazil.

Results: Most affected dogs were male (71%) neutered (95%) with an average age of 6.8 years. Ninety-one of the 100 affected dogs were brachycephalic. Otitis externa (OE; 81%) was the main non-neurological manifestation observed. The main neurological clinical manifestations observed were: "head tilt" (66%), ataxia (31%) and nystagmus (25%). Advanced imaging findings could not propose a presumptive diagnosis of tympanokeratoma in 60 of 100 (60%) of the dogs. The absence of tympanic membrane and the presence of a dense pearly yellowish material resembling keratin in the tympanic bulla, after myringotomy, was the main otoendoscopic finding. The advanced imaging findings did not correlate with otoendoscopy and histopathological findings in more than half of the dogs.

Conclusions And Clinical Relevance: Tympanokeratoma should be suspected in brachycephalic dogs with OE and peripheral vestibular syndrome, and samples of keratinous material from the middle ear associated with histopathological results may be the best approach for the diagnosis.