What Is Ear Cancer in Dogs?
Ear cancer in dogs refers to abnormal growths found on or within the dog’s ear. These growths can be either benign, meaning they grow slowly and do not spread, or malignant, growing rapidly and potentially spreading to nearby tissues or beyond.
The term “ear cancer” specifically refers to malignant tumors found within the ear of the dog, though not all ear tumors are cancerous. The ear consists of several parts including the pinna, external ear canal, middle ear, and inner ear. The pinna is the visible outer part of the ear, while the external ear canal is the tube leading into the ear. The middle ear contains small bones for transmitting sound, while the inner ear houses nerves for hearing and balance.
In dogs, ear cancer can affect any part of the ear, but it is more commonly found in the pinna or external ear canal rather than the middle or inner ear. The external ear canal has both vertical and horizontal components, with the eardrum marking the beginning of the middle ear. While ear cancer is relatively uncommon in dogs, it can pose serious health risks if left untreated.
Types
Types of ear tumors in dogs can be categorized into three main groups:
- Cancer affecting the pinna
- Cancer affecting the external ear canal
- Cancer affecting the middle or inner ear
Tumors located on the outer ear flap are more likely to be benign compared to those found inside the ear. Pinna cancers commonly involve skin cancers, with mast cell tumors and squamous cell carcinoma being prevalent types. Mast cell tumors originate from specific white blood cells found in connective tissue, particularly beneath the skin, while squamous cell carcinoma involves cancerous cells beneath the skin surface.
Cancer of the external ear canal is more frequently observed than cancer affecting the middle or inner ear. The predominant cancers affecting this region include ceruminous gland adenocarcinoma and squamous cell carcinoma. Ceruminous gland adenocarcinoma pertains to cancer originating from specialized glands responsible for secreting substances found in ear wax. Cancers originating in the middle or inner ear of dogs are considered rare occurrences.
Symptoms
The symptoms of ear tumors in dogs vary depending on where the tumor is located. Signs of a tumor on the pinna may include:
- Presence of a firm or soft mass on the ear flap
- Presence of a wound associated with the mass
- Scratching at the pinna
- Reacting with pain when the ear flap is touched
Tumors found in the external ear canal may be difficult to see, especially if they are deep within the canal. In such cases, feeling these nodules is typically not possible, and your veterinarian may require an otoscope to visualize the tumor unless it protrudes from the canal’s opening. Signs of tumors in the external ear canal include:
- Presence of a pink, white, or purple nodular mass within the canal
- Recurrent or chronic ear infections
- Inflamed, itchy, or painful ear
- Presence of waxy, pus-filled, or bloody discharge from the ear
- Foul odor emanating from the ear
- Headshaking
- Scratching at the ear
- Reacting with pain when the ear is touched
If the middle or inner ear is affected, similar signs to those of an external ear canal mass may be observed. However, your dog’s balance and neurological function may also be impacted. Symptoms in such cases could include:
- Head tilt
- Circling behavior
- Rolling
- Loss of balance and coordination
- Rapid eye movements, typically side-to-side
- Loss of hearing
- Facial paralysis, resulting in difficulty blinking or drooping of one side of the face
- Horner syndrome, characterized by different pupil sizes, drooping of the upper lid, sunken eye, and raised third eyelid
Causes
The causes of ear cancer in dogs are believed to involve recurrent or prolonged inflammation, along with genetic factors, which may contribute to its development. Chronic inflammation has the potential to progress to cancer over time.
Certain breeds are predisposed to different types of ear cancer. For instance, breeds like Cocker Spaniels, German Shepherds, and Pugs are more susceptible to ear cancer affecting the external ear canal or inner ear. On the other hand, dogs prone to skin cancer, such as Staffordshire Bull Terriers, American Bulldogs, Boxers, and Boston Terriers, are more likely to develop cancer on their pinna.
Diagnosis
Veterinarians diagnose ear cancer in dogs through various methods. During routine physical examinations, which should include an otoscopic examination of the ear canal, veterinarians may identify the presence of ear tumors, underscoring the importance of annual check-ups.
For tumors located on the pinna, veterinarians typically collect a sample of cells using a needle during the examination. These cells are then examined under a microscope to determine the type of tumor or whether it exhibits signs of malignancy. In some cases, a surgical biopsy, involving sending a sample to a reference laboratory, may be necessary for further analysis.
In instances where tumors are found in the external ear canal, veterinarians may utilize an otoscope to visualize the tumor. If accessible, veterinarians may perform an aspiration or biopsy of the tumor to ascertain its type.
Although most cancers of the external ear canal, middle ear, and inner ear do not metastasize and remain locally invasive, a computed tomography (CT) scan is often required to assess the extent of the tumor. If surgical intervention is being considered, a CT scan aids in surgical planning by providing detailed insights into the tumor’s location and size.
Treatment
The primary treatment option for ear cancer in dogs typically involves surgical intervention. In cases where the cancer affects the pinna, the preferred approach is surgical removal, which may involve partial or total removal of the ear flap (known as partial or total pinnectomy).
For tumors located within the ear canal, a more intricate surgical procedure called total ear canal ablation with lateral bulla osteotomy (TECA-LBO) is necessary. This procedure involves the complete removal of the ear canal. During the bulla osteotomy phase of the surgery, the bony structure at the base of the skull (tympanic bulla) is opened to eliminate secretory structures. Following this procedure, the dog will retain the ear flap but will no longer have an ear canal. While some hearing may still be present, it is often reduced or muffled.
Radiation therapy may be recommended for tumors that are too extensive for surgical removal, particularly those within the middle or inner ear. This therapy involves anesthetized procedures that are administered over multiple sessions across several days. In cases where tumors have metastasized, chemotherapy may be advised.
Supportive care for the dog will typically involve the administration of pain medications and antibiotics to manage any potential infections that may arise post-surgery or during treatment.
Living and Management
After undergoing surgery for ear cancer affecting the pinna or external ear canal, dogs often experience curative outcomes. To prevent your pet from disturbing their incision site, it’s important to ensure they wear a recovery cone following the surgery.
Given that this surgery involves the removal of a significant portion of the ear, which is closely linked to several crucial nerves, you may observe facial paralysis or balance issues post-surgery. Prior to the procedure, collaborate with your veterinarian to develop a comprehensive plan for managing potential side effects. If your pet experiences balance or coordination difficulties, take precautions to prevent accidents such as keeping them away from stairs and other elevated areas, and never leave them outside unattended.
In most cases, dogs exhibit an improvement in pain levels within a few days following surgery. It’s essential to coordinate with your veterinarian to establish an effective pain management strategy. Following the recovery period from surgery, most dogs adapt well to life with one functional ear and resume their usual affectionate behavior.
