What Is Ear Cancer in Dogs?
Ear tumors in dogs are any abnormal growths on or within the ear of the dog. Benign tumors tend to grow slowly and don’t spread (metastasize). Malignant tumors grow rapidly, invade local tissues, and sometimes metastasize.
Ear cancer refers to the subset of ear tumors that are malignant. Not all ear tumors are cancerous, but all ear cancers are tumors.
Cancer can affect any part of your dog’s ear—the pinna, external ear canal, middle ear, and inner ear. The pinna is the cartilaginous flap of the ear that either stands up or droops down. The external ear canal is the tube going into the ear that you can see when you hold up your dog’s pinna.
In dogs, the ear canal has both a vertical and a horizontal component. At the end of the horizontal component is the eardrum, which marks the start of the middle ear. The middle ear is a cavity (tympanic cavity) that contains three tiny bones that transmit sound to the inner ear. The inner ear contains nerves for hearing and receptors that are important for balance.
Ear cancer is uncommon in dogs. Ear cancer affecting the pinna or external ear canal is more common than cancer affecting the middle or inner ear.
Types of Ear Tumors in Dogs
Ear cancer in dogs can be classified into three groups:
Cancer of the pinna
Cancer of the external ear canal
Cancer of the middle or inner ear
Tumors on the ear flap are more likely to be benign than tumors inside the ear. Cancers on the pinna tend to be skin cancers, and common types include mast cell tumors and squamous cell carcinoma. Mast cell tumors are tumors of a specific white blood cell found in connective tissue, especially under the skin. Squamous cell carcinoma is cancer of the cells that form under the skin surface.
Cancer of the external ear canal is more common than cancer in the middle or inner ear. The two most common cancers affecting this outer part of the ear are ceruminous gland adenocarcinoma and squamous cell carcinoma. Ceruminous gland adenocarcinoma is cancer of the specialized glands that secrete materials found in ear wax.
Cancers originating in the middle or inner ear of dogs are rare.
Symptoms of Ear Tumors in Dogs
Symptoms of ear tumors in dogs vary depending on tumor location. Signs of a tumor on the pinna include:
A firm or soft mass on the ear flap
A wound associated with the mass
Scratching at the pinna
Reacting painfully when the ear flap is touched
Tumors in the external ear canal can be hard to see, particularly if they’re deep in the canal. You typically won’t be able to feel these nodules. Unless the mass protrudes from the opening to the external ear canal, your veterinarian will need an otoscope to see the tumor.
A pink, white, or purple nodular mass within the canal
Recurrent or chronic ear infections
Inflamed, itchy, painful ear
Waxy, pus-filled, or bloody discharge from the ear
Foul odor from the ear
Scratching at the ear
Reacting painfully to having the ear touched
If the middle or inner ear is affected, you’ll see most of the same signs you’d see with an external ear canal mass. However, your dog’s balance and neurologic function may also be affected.
Symptoms could include:
Loss of balance and coordination
Rapid eye movements, usually side-to-side
Loss of hearing
Facial paralysis, causing difficulty blinking or the face to droop on one side
Horner syndrome (different pupil sizes, drooping of the upper lid, sunken eye, third eyelid raised)
Causes of Ear Cancer in Dogs
Recurrent or long-term inflammation and genetics likely play a role in the development of ear cancer. Chronic inflammation can eventually lead to the development of cancer.
Breeds predisposed to ear cancer affecting the external ear canal or inner ear include Cocker Spaniels, German Shepherds, and Pugs. Dogs that are more likely to develop cancer on their pinna are those that are prone to skin cancer, such as Staffordshire Bull Terriers, American Bulldogs, Boxers, and Boston Terriers.
How Veterinarians Diagnose Ear Cancer in Dogs
Your veterinarian may see the ear tumor during a routine physical that includes an otoscopic exam of the ear canal—which is why annual exams are so important.
If the tumor is on the pinna, your veterinarian will use a needle to collect a sample of cells to look at under a microscope. With this sample, your veterinarian may be able to determine the type of tumor or if the tumor has signs of malignancy. Surgical biopsy (sending a sample to a reference lab) may be necessary.
For tumors in the external ear canal, your veterinarian may need an otoscope to view the tumor. If your veterinarian can reach the tumor, they may aspirate or biopsy the tumor to determine the type.
Most cancers of the external ear canal, middle ear, and inner ear do not metastasize but are locally invasive. A computed tomography (CT) scan is needed to determine the extent of the tumor. If you plan to pursue surgery, a CT scan helps with surgical planning.
Treatment of Ear Cancer in Dogs
The treatment of choice for ear cancer is usually surgical removal. For cancers that are on the pinna, this includes removing part of or the entire ear flap (partial or total pinnectomy).
Cancers within the ear canal require a more complex surgical procedure called a total ear canal ablation with lateral bulla osteotomy (TECA-LBO). With this procedure, the entire ear canal is removed.
In the bulla osteotomy portion of the surgery, the bony structure on the bottom of the skull (tympanic bulla) is opened to remove secretory structures. At the end of this procedure, your dog will have an ear flap but no ear canal. They may still be able to hear from this ear, but their hearing will be reduced or muffled.
Radiation therapy may be recommended for tumors that are too extensive for surgery, including tumors within the middle or inner ear. Radiation therapy is an anesthetized procedure that is repeated for a specified number of treatments over multiple days. For tumors that have metastasized, chemotherapy may be recommended.
Supportive care for your pet will include pain medications and antibiotics to manage infections.
Recovery and Management of Ear Cancer in Dogs
In cases affecting the pinna or external ear canal, surgery is often curative. To prevent your pet from scratching at their incision, ensure they wear a recovery cone after surgery.
Because this surgery involves removing a large portion of the ear, which is closely associated with several important nerves, you may notice facial paralysis or balance issues after surgery. Be sure to formulate a plan for management of side effects with your veterinarian before surgery. If they are having issues with balance or coordination, keep your pet away from stairs and other areas they may fall from. Do not let them outside unattended.
Most dogs will show improvement in pain levels within a few days of surgery. Make sure to work with your veterinarian to develop a good pain management plan. After recovering from surgery, most dogs will adjust to life with one functioning ear and return to their typical affectionate selves.
Featured Image: iStock.com/andresr
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