Ear Disorders - Merck Veterinary Manual

Deafness

Deafness—the absence of perception of sound—and reduced hearing are common in dogs and cats, and to a lesser extent in other species. Deafness can be hereditary or acquired, congenital or later onset, and sensorineural or conductive. The most common cause of deafness in dogs and cats is congenital and hereditary, associated with white pigmentation. Adult and geriatric animals are most likely to be affected by otitis, drug toxicity, noise trauma, and presbycusis.
- Deafness in Animals
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Diseases of the Pinna

A variety of dermatologic conditions affect the pinna. Rarely, a disease affects the pinna alone or the pinna is the initial site affected. As with all dermatologic conditions, a diagnosis is best made with the results of a thorough history, a complete physical and dermatologic examination, and with careful selection and evaluation of specific diagnostic tests. The following topics are not all-inclusive but include diseases that solely or commonly affect the pinna of domestic animals.
Otitis Externa

Otitis externa is inflammation of the external ear canal and is a common problem in dogs and cats. Signs can include head shaking, pain, malodor, erythema, erosion, ulceration, swelling, and/or ceruminous gland inflammation. Diagnosis is based on otoscopic examination, cytology, and culture. Treatment depends on the specific diagnosis. The inciting cause must be addressed to prevent recurrence.
- Otitis Externa in Animals
Otitis Media and Interna

Otitis media, inflammation of the middle ear (the tympanic bulla, the opening of the auditory tube, and the ear ossicles), is uncommon in veterinary medicine. Clinical signs include recurrent otitis externa, head shaking, pain with opening the mouth, Horner syndrome, dry eye, and facial nerve palsy. Otitis interna is inflammation of the inner ear (the cochlea, vestibule, and semicircular canals) and is rare in veterinary medicine. Clinical signs include ipsilateral head tilt, spontaneous horizontal or rotary nystagmus, and other signs of peripheral vestibular disease. Diagnosis of each is based on clinical suspicion and supporting imaging (CT, MRI). Management should focus on treatment of infections (systemic and topical), decreasing inflammation, and treating any contributing factors.
- Otitis Media and Interna in Animals
Tumors of the Ear Canal and Middle Ear

Ear canal tumors may arise from any of the tissues lining or supporting the ear canal, including the squamous epithelium, the ceruminous or sebaceous glands, or the mesenchymal tissues. Malignant tumors arising from the external ear canal and pinna are more common in cats than in dogs.