Chronic Ear Problems in Dogs

Otitis is an inflammation of the ear and it is one of the most frequent reasons for owners to seek a veterinarian's help. The prevalence of otitis externa, or inflammation of the external ear, in dogs has been reported to be between 10 to 20 percent although in more tropical climates it is probably closer to 30 to 40 percent. 

The term otitis does not refer to a specific disease, but it is a symptom of many diseases and not a specific diagnosis. 

Causes

Allergies, such as inhalant allergy and food allergy

Parasites such as ear mites

Endocrine diseases such as hypothyroidism

Auto-immune diseases like lupus

Tumors

Chronic inflammation stimulates the proliferation of the skin lining the ear canal. As a consequence, thickening of the canal occurs and leads to narrowing of the canal. More importantly the skin is thrown into numerous folds, and this inhibits effective cleaning and the application of medications. These folds act as a site for the perpetuation and protection of secondary micro-organisms like bacteria.

Inflammation of the middle ear (otitis media) results from chronic inflammation of the external part of the ear canal, rupture of the ear drum and establishment of infection in the middle part of the ear. Discharge in the tympanic cavity is difficult to treat with topical therapy and often remains as a source for infection. Otitis media is usually bacterial in origin. Clinical signs suggestive of otitis media include head shyness and pain on palpation of the ears. Some cases of otitis media might experience head tilt, circling and dry eyes, but the vast majority do not have neurological abnormalities.

As the ear drum quickly grows back after rupture, otitis media may also be present, even if an intact membrane is seen on otoscopic examination. Radiography cannot be used to completely rule out the presence of otitis media since 25 percent of confirmed cases had no radiographic evidence of the disease. In one study, otitis media was present in 80 percent of cases of chronic, relapsing otitis externa, so it must be considered as a possible cause of any refractory or relapsing otitis externa. Treatment of otitis media is based on bacterial culture and sensitivity results. Most cases require long term antibiotic therapy, a minimum of 2 months, and aggressive topical therapy.