Canine Otitis Interna Study Guide

Overview and Clinical Importance

Otitis interna is inflammation of the inner ear structures, including the cochlea (responsible for hearing) and the vestibular apparatus (responsible for balance). It represents the most severe form of ear disease in dogs and typically occurs as an extension of otitis media (middle ear infection). This condition is relatively rare compared to otitis externa but carries significant clinical importance due to potential complications including permanent hearing loss, chronic vestibular dysfunction, and life-threatening intracranial extension.

The inner ear is located within the petrous portion of the temporal bone and contains the sensory organs for both hearing (cochlea with organ of Corti) and balance (vestibular labyrinth with semicircular canals, utricle, and saccule). When infection or inflammation extends to these structures, patients develop characteristic peripheral vestibular signs that are important for NAVLE recognition.

Anatomy of the Canine Inner Ear

Bony and Membranous Labyrinth

The inner ear is housed within the bony labyrinth in the petrous portion of the temporal bone. This bony structure contains the membranous labyrinth, which is filled with endolymph and surrounded by perilymph. The inner ear has three functionally related parts: