Etiolog y of Ceruminous Otitis

When ceruminous glands and sebaceous glands of the ear canal become chronically irritated, the results are cystic dilation of ceruminous glands, hyperplasia, and increased activity of the overlying sebaceous glands.

Figure 10-1

Multiple openings of the cerumen glands along the ear canal.

Figure 10-2

Many diseases cause increased blood supply to the ears, increasing the metabolism within the ceruminous glands. Bacteria and yeasts secondarily grow on the roughened ear canal surface, using the glandular secretions as their nourishment.

With improper drainage and lack of air circulation (due to pendulous ears in some breeds), excessive growth of these organisms may occur within the ear canal.

In most cases of ceruminous otitis, the epidermal hyperplasia and inflammatory reaction occlude the external ear canal, making visual examination difficult. In both the dog and cat, hyperplasia of the ear canal can simulate neoplastic conditions that may lead to misdiagnoses and improper treatment. When hyperplasia does not respond to treatment and hardening of the ear canal ensues, surgical intervention is often the treatment of choice. Surgical opening of the ear canal allows proper drainage. The identification and treatment of underlying infections are important for surgical success.

Ceruminous otitis is inflammation of the glandular structures of the ear canal, with subsequent excessive epidermal proliferation and otitis externa that requires medical or surgical management. The causes of ceruminous otitis are many, and each condition is accompanied by other dermatologic or systemic manifestations.