Ceruminous Gland Adenocarcinoma in Dogs

What Is Ceruminous Gland Adenocarcinoma in Dogs?

Ceruminous gland adenocarcinoma is a rare cancerous (malignant) tumor that originates from the sweat glands found in the external auditory canal of a dog’s ear. The medical term for ear wax is cerumen. Ceruminous glands are responsible for producing ear wax. Ceruminous gland adenocarcinoma is only found in a dog’s ears and its surrounding structures. It always originates in the ear because it’s the only place in the body where ceruminous glands exist.  

Ceruminous gland adenocarcinomas begin to grow within the ear canal and are usually, but not always, distinguished from benign polyps (growth) by how they look. Generally, ceruminous gland adenocarcinomas are irregular in shape and ulcerate (break open) and bleed easily. In contrast, benign growths are smooth. 

Symptoms of Ceruminous Gland Adenocarcinoma in Dogs

Symptoms of ceruminous gland adenocarcinoma are similar to symptoms of a typical ear infection, except only one ear is affected. Common symptoms include: 

• Ear scratching 

• Head shaking 

• Discharge and a foul odor from the ear  

• Head tilt  

• Pain 

There is usually a greater volume of ear discharge with this type of tumor than with an ear infection, and the discharge may be bloody. If the tumor is large or affecting deep structures of the ear, your dog may show signs such as poor balance, walking in circles, dizziness, and falling to its side.  

Causes of Ceruminous Gland Adenocarcinoma in Dogs

The exact cause of ceruminous gland adenocarcinoma is unknown. However, it is suspected that chronic inflammation (swelling) of the ceruminous glands, like the type caused by chronic or recurrent ear infections, is a risk factor.  

This is another reason it is important to treat ear infections at their first sign and make sure they are fully healed before ending treatment. Treating ear infections promptly also prevents pain, ruptured ear drums, and deafness. Cocker Spaniels are more likely to develop ceruminous gland adenocarcinoma than other breeds. This may be related to their high risk for chronic ear infections.  

Ceruminous gland adenocarcinoma is the most common ear canal tumor in dogs but remains rare overall. It is more common in cats. 

How Veterinarians Diagnose Ceruminous Gland Adenocarcinoma in Dogs

Your veterinarian will examine the affected ear with an otoscope. This tool shines a light into your dog’s ear to examine the ear canal. Sometimes the tumor can be seen and diagnosed during the first vet exam visit.  

Depending on your dog and the diagnosis, your veterinarian may suggest a sedated ear exam. During this exam, your dog will be given medications to make them unconscious, then the ear will be flushed of all debris and a small camera is guided into the ear for further examination. 

Once the mass is found, your veterinarian may recommend a CT or a biopsy to determine the full extent of the mass. During a biopsy, your vet will carefully take a sample of the tumor. This tissue is examined by a veterinary pathologist to figure out whether it is a benign polyp (noncancerous) or malignant (cancerous).  

Treatment for Ceruminous Gland Adenocarcinoma in Dogs

Surgery is the only treatment option to provide dogs with a good prognosis for survival      . 

Before any surgery to remove a cancerous mass, your veterinarian will perform bloodwork and x-rays of the lungs to look for metastatic disease (cancer spread). They may also take samples of lymph nodes near the affected ear to look for metastasis. This is known as staging and helps your veterinarian know whether your dog is a suitable candidate for surgery and the likelihood of a surgical cure. 

The treatment for ceruminous gland adenocarcinoma is surgical removal. The most common surgery for this cancer is a total ear canal ablation (TECA), which involves removal of the entire ear canal, its associated structures, and a deep cleaning of the inner ear. Since auditory structures of the external and middle ear are always removed, and sometimes the inner ear, the dog will be deaf post-surgery in the affected ear. 

If the tumor is contained within the ear canal, this surgery typically cures the condition. If the tumor extends to the skull bones, then radiation or chemotherapy may be needed depending on the diagnosis.  

After the surgery, your veterinarian will follow up with you regarding the results from the pathologist’s report. The pathologist will examine the mass that was removed during surgery and will provide clarity about the type of cancer and whether all was removed.  

Recovery and Management of Ceruminous Gland Adenocarcinoma in Dogs

After the TECA surgery, your dog will most likely need medications and rest for several weeks. It’s important to give your dog time to recover from major surgery and to adjust to being deaf on the side of the face where the ear was impacted. Most dogs handle this adjustment well, and your vet can help provide further instructions on how to help your dog adapt to their new environment.  

It is important to give all the medications prescribed by your veterinarian to ensure proper healing.   

If you are worried about anything your dog does during the first few weeks of recovery from surgery, call your veterinarian and explain the symptoms. It’s also important to maintain follow-up visits offered by your vet to ensure a speedy and healthy recovery.