Tumors in the ear canal may originate from the lining of the ear canal or the glandular tissue responsible for the production of earwax and oily secretions. It may also arise from the bones, muscles, connective tissues, or other supporting tissues surrounding the ear canal. External ear canal tumors and tumorous outgrowths of the pinna are more frequently encountered than middle and inner ear tumors in dogs. Among the different breeds of dogs, Cocker Spaniels have the highest risk of developing tumors in the ear canal. Younger dogs have lesser chance of developing tumors compared to older dogs.
It is not known why tumors develop in the ear canal, but chronic inflammation is cited as one of the reasons that trigger changes in the tissue that may eventually become abnormal growths that turn into tumors. When the external ear is inflamed, it may lead to the thickening of the ear wax secreted by the glands, which in turn may lead to the cells in the ear canal becoming cancerous. The majority of the tumors originating in the ear canal are cancerous, even though benign tumors may also occur.
One of the symptoms of the tumors in the ear canal is an ear discharge that may be bloody or containing pus issuing from the affected side only. It may have a foul odor too. The dog may show its irritation by scratching the affected ear constantly and by head shaking. There may be a swelling of the area around the ear with additional abscesses that drain pus. Deafness in the affected ear is common. Loss of balance and a tilting of the head indicate the involvement of the middle ear. The dog may be disoriented too. The veterinarian may suspect a tumor in the ear canal when a one sided inflammation of the ear does not get resolved by other treatments.
Earwax Gland Tumors
The glands that secrete earwax are located in the ear canal. They may develop tumors that may be benign or cancerous. Earwax gland tumors are more frequently encountered in dogs that are middle-aged or older. Dogs that have had chronic inflammation in the ear canal are at a higher risk of developing these tumors which are mostly malignant. Cocker Spaniels are especially known for their susceptibility to cancerous ear wax gland tumors.
Tumors of the earwax gland typically have a pink-white color and a dome shape, often appearing to have a stalk, but they may appear as flat patches too. There may be sores on these patches that are slow to heal. Since these tumorous growths usually cause obstructions in the ear canal, not only the external ear, but the middle ear may also become inflamed. A discharge containing pus or blood may be present, along with loss of balance typical of middle-ear disorders. The nearby lymph nodes may be involved, and the cancer may even spread to the salivary glands, hence their removal is generally recommended.
Non-cancerous tumors of the ear canal may be surgically removed to bring about a permanent cure in most of the cases. Laser surgery is preferred over the traditional method wherever possible. To treat malignant tumors of the ear canal, other treatments such as radiation and chemotherapy may be necessary even after the removal of the cancerous tissue. The complexity of the surgery is proportionate to the spread of the cancer and the involvement of adjoining tissues. Dogs with fairly uncomplicated malignant tumors that get removed completely by surgery may have a 5-year survival time, but if the cancer is extensive it is reduced to less than a year even with radiation therapy to destroy the parts of the tumors that could not be removed surgically.
The veterinarian may counsel you on the options available considering the overall health of the dog and the probable outcomes of the different types of treatment.