Ear Cancer In Dogs

A dog’s ears can be pointy or rounded, droopy or cocked, folded or floppy. No matter the shape, hidden deeper within are the ear canals. That’s where the glands that produce ear wax (also called “cerumen”) are located. Though uncommon, these ceruminous glands can be a source of cancer. Despite the proximity to the brain, the eyes and the jaw, ear cancer in dogs can often be treated with surgery, radiation and/or chemotherapy. In some cases, it can be cured. It’s worth noting that an ear canal tumor in a dog can be benign (non-cancerous), too.

Tumors also can appear on the skin of a dog’s ear. One example of a tumor on a dog’s ear flap is a mast cell tumor. However, for the information presented here, “ear cancer in dogs” is in reference to tumors within the ear canal itself. Fortunately, cancer called ceruminous gland carcinoma or ceruminous gland adenocarcinoma is rare. Dogs that develop this type of cancer typically are 10 years of age or older. There is some thought that dogs prone to chronic ear infections, such as cocker spaniels, are more predisposed to ceruminous gland cancer. This type of cancer often does not metastasize (spread), but if does, it could go to the submandibular lymph nodes (in the jaw area) or the lymph nodes in the shoulder region. These carcinomas can also metastasize to the lungs.  More often, however, it will spread deeper into the ear canal or even through the skull, possibly affecting the brain.

As with any type of cancer, early treatment can lead to a better prognosis. Thus, knowing the symptoms and what to expect can be very helpful if you are concerned about your dog possibly having an ear tumor.

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Types of Dog Ear Tumors

As mentioned above, not all tumors in or on a dog’s ear are cancerous. Examples of benign tumors include:

• Ceruminous gland adenomas
• Sebaceous gland adenomas
• Polyps
• Basal cell tumors

Examples of a dog inner ear tumor that is cancerous include:

• Ceruminous gland adenocarcinoma
• Squamous cell carcinoma

Symptoms of Ceruminous Gland Carcinoma in Dogs

An ear canal tumor in a dog might not be noticed unless you are specifically examining the dog’s ears and the tumor is big enough to be visible. However, other signs may convince you that something is wrong and that a vet visit is in order. You may notice an odor emanating from the ear, or waxy or bloody discharge. An ear infection that hasn’t resolved after an extended time span also can be a sign. Your dog also may shake his or her head or scratch the ear more than usual or shy away when you reach to pet him or her.  At times, the ear may be uncomfortable or painful.

Since parts of the inner ear also help control a dog’s equilibrium, or sense of balance, a tumor within also can make it appear that your dog is dizzy or off-balance while walking. This sensation can also result in a dog tilting his or her head in an abnormal fashion.

Diagnosing Ceruminous Gland Ear Cancer in Dogs

Regardless of the symptoms being displayed, a veterinarian will run a series of tests in order to confirm or dispel a suspected diagnosis of ceruminous gland adenocarcinoma in a dog. These may include:

• Bloodwork: A complete blood count (CBC) and a blood chemistry profile help a veterinarian assess the dog’s overall health, which factors into which treatment course is best.
• Three-view X-rays: Imaging of the chest cavity is recommended to assess whether or not there is any metastatic disease (spread of cancer) to the lungs.
• Otoscopy: This procedure entails a veterinarian using a tool called an otoscope to examine structures within the inner ear. At times, a dog will be anesthetized for deep and more thorough evaluation.
• Biopsy: If the presence of a mass is confirmed, a veterinarian may try to extract at least a portion of the tumor so that it can be analyzed by a pathologist. A pathologist looks at tumor characteristics such as the mitotic rate — how fast cells are dividing — to determine how aggressive the cancer is.
• Fine needle aspiration: If aregional lymph node is of concern for spread of disease, a fine needle aspiration can be used to collect a sample. These cells would be provided to a pathologist for further examination.
• CT Scan: In some cases, a CT scan might be recommended prior to treatment to assess the extent of the disease in the ear canal, the surgical feasibility and in preparation for radiation therapy.

Treatment and Prognosis

Surgery

Since a diagnosis of ceruminous gland adenocarcinoma in a dog means the tumor is malignant, surgical removal is often the treatment of choice. In such cases, a CT scan might be ordered to determine how infiltrative the tumor is and to help the surgeon better map out the procedure. Depending on the case specifics, the surgery can be complex: A total ear canal ablation (TECA) may be indicated, which entails removing the entire ear canal and along with some bone tissue. The goal with removal is to get wide, clean margins, which means a specified depth of the edges of the removed portion are cancer-free. This would indicate that the entire malignancy has been removed. Dogs typically don’t seem to have issues from undergoing a TECA, and they can still hear with the other ear.

If a dog ear tumor is benign, removal with clean margins can be curative.

Radiation Therapy

If the entire cancerous mass cannot be removed during surgery, post-operative radiation therapy is an option. That also holds true if the dog’s family declines the TECA procedure for any reason. Radiation is also an option if the disease is locally extensive, for example if the skull or the brain is involved as a result of local progression of the mass. Dogs tend to do well with radiation treatment.

There are two primary types of radiation: conventionally fractionated radiation therapy (CFRT) and Stereotactic Radiation (SRS). The objective is to destroy or at least slow down cancer cells by directing high-energy rays at them. SRS is the more advanced option, using higher dosages and precision targeting. SRS also typically requires just one to three treatments, whereas CFRT requires 15 to 21. Since anesthesia is required for radiation, this is another benefit of SRS. The significantly reduced number of anesthetic events can be an important consideration, especially for older dogs or those with additional health issues.

Chemotherapy

Chemotherapy may be recommended for aggressive and/or systemic cancers (those that have spread). This might be the case if the pathology report shows a very aggressive ceruminous gland adenocarcinoma in a dog — for example, if the cancer has a high mitotic rate (fraction of cells dividing), has invaded into the blood vessels or has spread to the lymph nodes.

Forgoing Treatment

If ceruminous gland adenocarcinoma is left untreated, the tumor will continue to grow. Eventually, it will become troublesome for the dog. His or her ears could begin to smell bad. Discomfort might lead to a loss of appetite and lethargy, at which point the pet parent(s) may face a decision about euthanasia based on quality of life.  In the event of pain or discomfort, pain medications are recommended.

PetCure Oncology Treats Ear Cancer in Dogs

PetCure Oncology offers a wide range of options for treating a dog ear tumor, whether it is a tumor on the dog’s ear flap or within the ear canal. We specialize in SRS radiation therapy. We also live by our motto: “We Understand. We Commit. We Will Help.” Our mission is to help provide your pet with the best quality of life possible and extend your time together. For more information about our treatments and compassionate approach, find a location near you and contact us today.

The contents of this article were provided in part by Dr. Renee Alsarraf, DVM, DACVIM (Oncology), a board-certified veterinary medical oncologist and member of PetCure Radiation Oncology Specialists (PROS).