Total Ear Canal Ablation

Figure 1. The ear canal (gray arrow) is upright/vertical near the external opening, then becomes flat/horizontal as it approaches the eardrum. The middle ear (black arrow) is separated from the ear canal by the eardrum (“tympanic membrane”). The middle-ear bony chamber (bulla) contains openings to the inner ear, where the organs of hearing and balance are located.

Otitis externa is inflammation of the external ear canal. Because a dog’s ear canal is L-shaped (Figure 1), fluid does not drain easily from the canal openings. In addition, the canal lining can become inflamed and thickened, which restricts airflow and fluid movement in and out of the canal. Dogs with otitis externa may also develop otitis media (inflammation of the middle ear). Similar to what can happen in children (especially after airplane flights), fluid may accumulate behind the eardrum, creating pressure and pain. Otitis externa and otitis media are common in dogs, particularly in certain breeds such as Cocker Spaniels and German Shepherds.

In puppies and kittens, otitis externa is frequently caused by ear mites—tiny parasites that cause intense itching and a thick brown discharge. In adult dogs, allergies are the most common underlying cause, whether environmental sensitivity or food-related. In older animals, tumors can obstruct the ear canal and lead to secondary infection. Other predisposing factors include foreign bodies (e.g., grass awns/seeds), narrow ear canals (often in Shar Peis), and long, floppy ear flaps (for example, Basset Hounds) that limit airflow. Hormonal disorders (such as low thyroid function) and other underlying skin conditions may also contribute.

Figure 2: A Cocker Spaniel with severe otitis externa in both ears. Note the pronounced cauliflower-like thickening in the ear canal region.

Dogs may initially show mild signs, but symptoms can worsen over time or after unsuccessful treatment attempts. Common signs include:

• scratching at the ears or shaking the head
• redness, thickening, or hair loss on the inner/less-haired surface of the ear
• a strong, unpleasant odor from the ears
• progressive blockage of the ear canal with a cauliflower-like appearance (Figure 2)
• thick white discharge when bacterial infection is present

Because the disease is painful—especially if the middle ear is involved—pets may develop behavior and personality changes. They may avoid being touched on the head and may be uncomfortable opening the mouth widely or chewing. Canal obstruction can also dampen hearing, making dogs less responsive to their owners.

Figure 3: CT scan of a pug with ear canal obstruction (green arrow) from chronic infection. The middle ear (red arrow) contains fluid and tissue, and the surrounding bone has thickened.

Unless there is a tumor, foreign material, or canal narrowing/obstruction, otitis externa is usually managed medically. Before treatment, the primary care veterinarian should identify the underlying cause. Diagnostic steps may include:

• Otoscopy: examination of the canal with a lighted scope to look for abnormalities and obtain samples to assess for yeast, bacteria, or mites
• Culture of ear discharge: to identify bacterial species and determine antibiotic sensitivity
• Radiographs or CT: to evaluate the canal and determine whether the middle ear is affected (Figure 3). If the ear canal cartilage has become inflexible and calcified, surgery is likely required.
• Blood testing: thyroid function and blood chemistries to look for systemic illness
• Allergy evaluation: allergy testing and/or skin scrapings to assess allergic disease

Medical management is preferred when there is inflammation and discharge but no canal blockage. The canal is cleaned and flushed, and in some cases the veterinarian may need to drain the middle ear to relieve fluid buildup. Therapy is directed at the organism present (mites, bacteria, or yeast). Pain medication may be provided because ear infections are uncomfortable. Dogs with allergies may need allergy injections and/or dietary changes.

If the canal is obstructed due to a tumor, traumatic separation, calcification, or other blockage, ear canal removal may be necessary. This is a complex procedure and should only be performed by an ACVS board-certified veterinary surgeon.

Surgical Options

Total Ear Canal Ablation and Bulla Osteotomy
When the canal is completely calcified or obstructed by a markedly thickened lining or a tumor, the entire ear canal may need to be removed (Figure 4). The ear flap remains, although in dogs with erect ears (e.g., shepherd-type breeds) it may droop slightly afterward. The surgeon must also open the middle ear (bulla) to remove diseased lining and allow drainage. Because canals affected by otitis externa/media are often severely thickened and inflamed, the surgery can be lengthy and demanding, and pain medication is typically needed for several days after recovery.

Vertical Ear Canal Ablation
In some cases, only the vertical portion of the canal is diseased while the horizontal canal remains normal. Then only the vertical segment may be removed. This is less complex than total canal ablation and does not require opening and cleaning the middle ear. However, even if a vertical ablation is planned, the surgeon may determine during surgery that disease extent requires removal of the entire canal.

Lateral Ear Canal Resection (“Zepp”) Procedure
By opening the side wall of the canal, airflow and drainage can improve and owners can more easily clean and medicate the ear (Figures 5 and 6). Most dogs, however, do not improve substantially after this surgery, so it is usually limited to dogs that are born with narrow ear canals.

Figure 4. Final appearance after skin closure; local anesthetic is being injected to improve postoperative comfort.
Figure 5. The lateral canal wall is opened and a “drain board” is created from the outer canal wall.
Figure 6. Ten days after a lateral ear canal resection: a Q-tip rests on the drain board, and the horizontal canal lies just above it.

Figure 7. Facial nerve paralysis and head tilt. This pug had facial nerve and inner ear damage from severe chronic inflammation before surgery: the left lip and tongue drooped, eye ointment was required because blinking was impaired, and the head tilted left. These changes were permanent.

Most pets are discharged within 3–7 days, depending on comfort.

Typical postoperative restrictions and care include:

• an E-collar to prevent scratching at the incision
• eye drops for two weeks if the blink reflex is reduced
• oral pain medications
• antibiotics if there is severe infection
• suture removal 10–14 days after surgery (if sutures are present)
• lifelong management of underlying causes (e.g., allergies or hypothyroidism) to prevent recurrence of clinical signs

Potential postoperative complications include:

• facial nerve injury, leading to reduced or absent blinking on the operated side; this occurs in 25–50% of dogs, and in 10–15% it is permanent
• head tilt (Figure 7) due to balance disturbance
• intermittent drainage months to years later if infectious or secretory tissue remains after the initial surgery

Because many dogs with severe otitis externa already have reduced hearing before surgery, owners often do not notice a major change in hearing afterward.

Owners of predisposed breeds (such as Cocker Spaniels) should anticipate ear disease risk. These dogs should have ear checks once or twice yearly, and infections should be treated promptly to prevent chronic inflammation and canal thickening. Dogs prone to skin or food allergies should also be evaluated annually.

Prognosis after surgery for otitis externa/media depends on the underlying cause. Total ear canal ablation with bulla osteotomy successfully resolves ear drainage and discomfort in 90–95% of dogs, but recurrence can occur if allergies or other underlying disease is not controlled. Long-term success is much poorer when lateral ear canal resection is performed in dogs with severely diseased canals.