Ceruminous Gland Adenocarcinoma of the Ear in Dogs
More common in cats than dogs, ceruminous gland adenocarcinoma is the primary malignant tumor of the sweat glands that is found in the external auditory canal. Though rare, it is one of the most common malignant tumor of the ear canal in older dogs. And while it may be locally invasive, it has a low rate of distant metastasis (spreading of the cancer).
In addition, there is no known gender predisposition for this type of tumor, but Cocker spaniels may be more at risk.
Symptoms and Types
Similar to otitis externa, dogs with ceruminous gland adenocarcinoma exhibit vestibular signs such as dizziness, tilting of the head, uncoordination, and frequent stumbling. Local lymph node enlargement may also be seen. Other symptoms depend on the stage of the cancer.
Early stages of nodular masses:
- Pale pink
- Break off easily
- Open ulcers
- Large mass(es) which fill the canal and invade through the canal wall into surrounding structures
Experts are still uncertain of the exact cause for this type of adenocarcinoma, but chronic inflammation may play a role in tumor devlopment.
Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms and your dog's health history leading up to the onset of symptoms.Standard tests include a complete blood profile, chemical blood profile, a complete blood count, and a urinalysis.
Radiographic and CT (computed tomography) imaging are essential to confirming the diagnosis. Skull X-rays, for example, can help to determine if the tympanic bullae (the bony extension of the temporal bone in the skull) are involved in the mass. And thoracic X-rays and CT scans help identify if the cancer has spread (metastasized) to other organs. A tissue sample for biopsy will be essential for determining the exact nature of the growth.
Ear canal ablation (complete removal of the ear and ear canal) and lateral bulla osteotomy (removing the bony part of the ear canal) are preferred over lateral ear resection (removal of the majority of the ear). This is because these methods may extend your pet's survival time by three to four times when compared with lateral ear resection, which is typically only nine months. On large masses or those found to difficult to remove, radiotherapy should be performed.
Living and Management
Unfortunately, there is a poor prognosis associated with extensive tumor involvement and neurologic signs (dizziness, falling, head tilt, etc.). Your veterinarian will schedule follow-up appointments for your pet 1, 3, 6, 9, 12, 18, 21, and 24 months after treatment for a routine physical exam and chest X-rays.