Dogs and, less frequently, cats are commonly affected by infections of the ear. Many times, the infection is caused by yeast or bacteria and is easily treated with medications, such as ear flushes and antibiotics. Some animals, though, are susceptible to repeated ear infections. Cocker spaniels are notoriously susceptible to repeated ear infections as are other breeds who are commonly affected by skin disorders.

The anatomy of a dog’s ear makes it more difficult to treat infections. The external ear of the human (the part of the ear that extends from the eardrum to the outside) is short, straight, and horizontal. This allows any fluid that might accumulate to drain straight out; it also makes it easy to get ear medication all the way to the eardrum. The dog’s ear is very different. The external ear of the dog is shaped more like a funnel, with one portion (the vertical ear canal) that goes straight up and down, and a smaller portion (the horizontal ear canal) that takes a 90 degree turn from the bottom of the vertical canal and courses to the eardrum. This anatomy makes it difficult for fluid in the ear to drain out (because it has to fight gravity and travel upwards through the vertical canal before it can get out) and makes it difficult to get medication all the way down to the ear drum.

Chronic otitis externa is the term that describes long standing or repeated infections of the external ear canal. It is associated with anatomical and physiological changes to the external ear. In the face of long standing infection, the skin that lines the ear becomes inflamed and thickened. This makes the horizontal and vertical canals even smaller which makes it even more difficult for infection fluid to drain. The inflammation triggers ear wax and inflammatory fluid production, which creates a substance in which bacteria thrive. The normally pliable cartilage that helps form the ear becomes calcified (in essence, it turns to bone) which also can interfere with drainage. Finally, the infection in the external ear can erode through the ear drum, spreading the infection to the middle ear.

Treatment of ear infections depends on the severity of the problem. Simple infections can usually be treated successfully medically. In cases where the infection does not respond to medical management, or in cases where the infection recurs, surgery might be necessary. There are two basic types of surgery for the treatment of ear disease. The first surgery is designed to alter the anatomy of the dog’s ear to make it more like the human ear. It involves either removing the entire vertical canal (called a Vertical Canal Ablation) or just the wall of the vertical canal (called a Lateral Wall Resection, or a Zepp Procedure). This will result in the horizontal canal opening directly to the outside (leaving a short, straight, horizontal canal, just like the human ear). This surgery needs to be performed early, before there are changes that cause the horizontal canal to be excessively narrowed. It is also sometimes combined with a procedure (called a Bulla Osteotomy) that opens and cleans the middle ear if there is extension of the external ear infection to the middle ear.

The second surgery is a more radical surgery. It is considered to be a salvage surgery that is done when no other treatment will work. This surgery is called a Total Ear Canal Ablation and involves removal of the entire ear canal (vertical and horizontal), the ear drum, and part of the middle ear. This surgery will permanently remove the infected ear canal and allows the middle ear to be drained. It is usually a very good procedure for permanently resolving long standing and painful ear infections. In theory, this surgery, if performed on both sides, will make the dog near deaf because it removes the whole sound amplification system of the ear. However, most dogs are near deaf anyway before this surgery because of the extent of their ear disease, and most owners report that their dog can still hear, although not quite as well as normal, even if both ears are operated on.

Most dogs respond quickly to surgical treatments for ear disease. The vertical canal ablation and lateral wall resection surgeries do sometimes require continued treatment of the ears, but the treatment is usually easier to perform and is needed less frequently. Many dogs do not require any treatment at all after these surgeries are performed and the active infection is brought under control. The key to successful vertical canal ablation and lateral wall resection is to perform the surgeries early, before a lot of damage has been caused to the ear by the infection. If the damage has reached a point where these two surgeries are not options, then total ear canal ablation is the treatment of choice.

The preceding information was written by Dr. George Siemering and Dr. Dan Brehm. Drs. Siemering and Brehm are the surgeons at SouthPaws and perform a full range of soft tissue, orthopaedic, and neurological surgical procedures. They can be reached at (703) 451-0909.

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