These tumors are polyp-like growths with a narrow base or a stalk. Some are nodular overgrowths secondary to inflammation but others are benign or malignant cancers of the glands found in this area. Most are from the specialized sweat (ceruminous) glands of the ear. These glands produce watery secretion (cerumen) that keeps the ear moist. A few tumors arise from the sebaceous glands that produce an oily secretion and a few originate from the surface epithelium (squamous cell carcinomas). Malignant tumors may spread to other parts of the body.
What do we know about the cause?
The reason why a particular dog may develop this, or any cancer, is not straightforward. Cancer is often seemingly the culmination of a series of circumstances that come together for the unfortunate individual.
Inflammation of the external ear canals leads to cysts and overgrowth of the glands. The resulting polyps continue to cause mechanical problems and further inflammation. There is a tendency for the multistep process of tumor progression to occur although some inflammatory polyps and benign cancers never progress past the first stages and remain benign. Others progress rapidly.
Why has my dog developed this cancer?
Some dog breeds have ear canals that are partially enclosed (by drooping ears) and continually moist with a tendency to bacterial and yeast infections. Others have infection with mites. All these factors increase inflammation with swellings and possible transformation to cancerous growths.
Are these common tumors?
These are relatively common tumors in dogs. The Cocker Spaniel has an increased risk of developing the tumors.
How will this tumor affect my pet?
The most obvious effect is pain and itching of the ears. Lumps or polyps can be seen in most cases but sometimes there is simply ulceration and bleeding. They are invariably infected.
Malignant cancers may spread through the body by invading the lymph transport system. Further lumps may appear below the affected ear.
How is this cancer diagnosed?
Clinically, it is not possible to distinguish with certainty between those lumps that are still non-cancerous and those that are malignant and will spread. Definitive diagnosis relies upon microscopic examination of tissue. Cytology, the microscopic examination of cell samples, is misleading. Full diagnosis, prediction of behavior (prognosis) and a microscopic assessment of whether the tumor has been fully removed rely on microscopic examination of tissue (histopathology). This is done at a specialized laboratory by a veterinary pathologist. The piece of tissue may be a small part of the mass (biopsy) or the whole lump. Only examination of the whole lump will indicate whether the cancer has been fully removed but full removal is often difficult.
What treatment is available?
The most common treatment is surgical removal of the lump(s). Laser surgery is very effective when it is available. Sometimes extensive surgery is required and it is necessary to open up (ablate) the whole ear canal.
Can these disappear without treatment?
The cysts and polyps due to inflammation sometimes decrease in size if the inflammation is reduced. However, cancer rarely disappears without treatment. As development is a multi-step process, it may stop at some stages. The body’s own immune system can kill cancer cells but it is rarely 100% effective. Rarely, loss of blood supply to a cancer will make it die but dead tissue in this site will need surgical removal.
How can I nurse my dog?
Preventing your dog from rubbing or scratching its ears will reduce itching, inflammation, ulceration, infection and bleeding.
After surgery, the operation site needs to be kept clean and your pet should not be allowed to interfere with the site. Any loss of sutures or significant swelling or bleeding should be reported to your veterinarian. Specific treatment for this area may include the use of topical medication and special collars to prevent scratching.
How will I know if the cancer is permanently cured?
’Cured’ has to be a guarded term in dealing with any cancer.
Histopathology will give your veterinarian the diagnosis that helps to indicate how it is likely to behave. The veterinary pathologist usually adds a prognosis that describes the probability of local recurrence or metastasis (distant spread).
In most cases, surgery results in a complete cure. Sadly, there are some cases where the diagnosis and prognosis indicate that surgical removal will only give remission and the cancer will recur or spread.
Are there any risks to my family or other pets?
No, these are not contagious problems and are not transmitted from pet to pet or from pets to people.
Based on material written by Joan Rest, BVSc, PhD, MRCPath, MRCVS. and modified with permission from Lifelearn Inc.
© Copyright 2004 Lifelearn Inc.
