What is Otitis Externa?

Inflammation of ear canal, otitis externa (OE), is a common reason for doggies to be presented to the veterinarian. To understand the cause of the disease, we need to understand the basic anatomy of their ears. A dog's outer ear consists of the ear flap which can be upright or floppy. The ear canal is long narrow and in L-shape ( vertical and horizontal ) as it travels to ear drum. Some breeds such as poodle and schnauzer have very hairy ear canal. This special conformation of ears allows moist and heat trapped especially with floppy ears. This environment favors yeast and bacteria growth thus predispose to the OE. If OE has not been treated and controlled well, the ear canal epithelium becomes thicker and the lumen will be narrower by time thus more heat and moist being trapped. Eventually, the ear canal is obstructed completely in severe case. Other possible causes of external otitis could be due to food allergy, endocrine disease or immune-mediated disease which also predispose yeast and bacteria growth.

Clinical Signs of Otitis Externa

Clinical signs of OE include headshaking, scratching of ears, warm and redness of the ear flaps. Many owners are able to notice the sign at home. We have more cases during summer time due to the hot and humid weather in Hong Kong.

Treatment of Otitis Externa

To confirm the diagnosis of OE, sampling of ear discharge or wax is necessary. A veterinarian will make a smear on a slide and exam microscopically. Otoscopic examination is sometimes not possible because the ear is painful, swelling and filled with discharge. Sedation may be recommended sometimes. Microbial culture of the ear discharge and radiography of tympanic bullae may require in complicated or severe cases.

Treatment of OE depends on the suspected or known cause of OE. Management of pain and itchiness must be included in the initial treatment plan. Effective treatment may require both topical and systemic antimicrobial therapy along with ear wash and pain relief. If OE becomes chronic and the ear canal eventually obstructed, a surgical procedure is required to remove the vertical part of the canal and allow the horizontal part to be exposed.

Recommendation

Regular ear cleaning is important. It is recommended having your dog's ear cleaned once or twice weekly. As I mentioned above, not all OE in dogs are due to the special conformation of the ears. However, some dogs have primary cause of OE such as food allergy, endocrine or immune-mediated disease. Therefore, visiting veterinarian is important to find out the reason of OE besides trying hard to clean your dog's ears.