Otitis interna describes inflammation of the innermost portion of the ear responsible for hearing and balance. Dogs with otitis interna have a head tilt toward the affected side; they may be circling or staggering due to loss of balance. The cause of otitis interna most commonly originates from an untreated middle ear infection. Rarely, internal ear inflammation results from a tumor. Diagnosis of otitis interna begins with a physical examination to rule out other neurologic abnormalities. To determine the full extent of the inflammation, imaging (such as a CT scan) is necessary. Treatment for otitis interna requires long term use of systemic antibiotics to treat the infection. In severe cases, surgery may be required to mechanically remove the debris and infection from deep within the ear. Follow-up appointments are critical to the resolution of otitis interna.