Canine Ear Infection

Ear infections are one of the most common reasons for dog owners to visit the veterinary hospital. It is estimated that ear infections occur in 15-20% of dogs, but some breeds are prone to have an ear infection. Most common breeds that show ear infection are Cocker Spaniels, American Cocker Spaniel, English Cocker Spaniel, Labrador Retriever, Poodles, and Schnauzers. However, this disease may occur in any breed.

Like human ears, ear wax (cerumen) is secreted by glands in the ear canal of dogs daily, and ear waxes consist of a dead cell, debris or microorganism. In healthy dogs, ear waxes are not accumulated in the canal because they are removed naturally with the gradual migration of epithelium in the canal toward the opening of the ear canal. However, ear waxes can be accumulated in the ear canal if there is any change to prevent this natural removal of them. Accumulated ear waxes can provide a good microenvironment in the ear canal for bacteria and yeast to overgrow. Which causes overproduction of ear waxes and inflammation in the skin of the ear canal (ear infection). An ear infection can happen in the external portion of the ear canal or middle ear or inner ear.

Some of the signs that owners may observe in their dogs at the early stage of ear infections are head shaking, scratching at their ears, malodor, whining or discomfort. These signs are due to pain and waxy ear discharge. Sometimes fluid can be accumulated in the ear flap known as an aural hematoma. It is due to a rupture of the blood vessel in the pinna when dogs are shaking their head vigorously and scratching at their ears aggressively. If a dog shows these clinical signs, it is strongly recommended to see a veterinarian to treat ear infection as soon as possible. It is much easier to treat at the early stage of ear infection, and it also prevents the ear canal from developing permanent structural change.

At this stage, most veterinarians examine the dog’s ear with an otoscope to determine how severe and painful ear infection is. They also check whether the eardrums are intact or whether any foreign body or polyps exist in the canal. The microscopic exam is the next step after collecting a sample of their ear discharge. It will help to determine which organisms are causing infection and to find the right medication to treat the ear infection. If an animal has an aural hematoma, the fluid can be drained, however, the hematoma is likely to recur and may need to be drained numerous times.

If ear infections are untreated for a long time or recur frequently, dogs are likely to have a chronic ear infection, which may lead to structural changes in the ear canal. Such as the proliferation of epithelium in the canal or narrowing or occlusion of the canal. If this stage continues, an ear infection may cause rupture of the eardrum or can spread to the middle ear. An animal with middle may show head tilt or lack of balance. In these cases, sometimes it is very difficult to treat medically; therefore, it may require surgical removal of the ear canal to resolve the painful chronic infection.
Therefore, checking the ear by a veterinarian as early as possible is critical to prevent a dog’s ear infection from becoming chronic ear infection.

Written by: Dr. Cho, DVM