Cancer in a Cat's Ear: Tumors and Warning Signs

Name: Cancer in a Cat's Ear: Tumors and Warning Signs
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Cancer in a cat's ear is a tumor that grows from the skin, glands, or deeper tissues of the ear canal or the ear flap. In cats, these tumors are more often malignant than benign, especially after age 11, and they are frequently mistaken for a long-standing ear infection [1]. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

A lump, sore, or one-sided discharge that does not clear up with standard ear infection treatment should be checked for a tumor [1].
Malignant ear canal tumors are more common in cats than in dogs, and malignancy becomes more likely with age and with chronic ear disease [1][2].
Diagnosis requires a tissue sample (biopsy), not just a visual exam, because tumors and infections can look alike [3].
Surgery is the most common treatment, and cats treated surgically for one type of ear cancer lived longer than cats treated with medication alone in one case series [4].
Any new mass, non-healing sore, or bloody discharge from one ear deserves a veterinary visit, not another round of ear drops.

What Cat Ear Cancer Actually Is

The ear has three parts: the outer flap (pinna), the ear canal, and the middle and inner ear. Tumors can start in any of them. Most feline ear tumors begin in the external canal and outer ear, which are easier to see than tumors deeper inside [1].

These growths come from the tissues that line or support the ear canal. That includes the flat surface skin cells, the wax-producing ceruminous glands, the oil-producing sebaceous glands, and the connective tissue, muscle, and bone beneath them [1][2].

The most common tumor of the cat ear canal is the ceruminous gland tumor, which arises from the wax glands [3]. Ceruminous gland adenocarcinoma is the most frequently reported malignant tumor of the feline external ear canal [4][5]. Squamous cell carcinoma is the most common malignant tumor found in the feline middle ear [4]. In a review of 124 ceruminous gland tumors from dogs and cats, most of the masses in both species were malignant [6].

Benign tumors exist too, and middle-aged cats are more likely to have them. Cats over 11 years old are more likely to have malignant tumors, and that pattern appears tied to how long the ear has been diseased instead of to age alone [2].

Warning Signs of a Cat Ear Tumor

Owners often notice something is wrong long before a diagnosis is made. The trouble is that the early signs look like an ordinary ear infection.

Signs you can see or smell

Discharge from one ear that keeps coming back. It may be waxy, pus-filled, or bloody [1].
A foul odor from the affected ear [1].
A firm, pinkish mass that fills or blocks the ear canal [3].
A lump or sore on the ear flap that does not heal.
Swelling around the ear or a draining abscess below the ear [1].

Signs you can see in your cat's behavior

Head shaking and scratching at one ear [1].
Pain when the ear is touched.
A head tilt, loss of balance, or other neurological signs if the middle or inner ear is involved [1].
Deafness in the affected ear [1].

The pattern that should raise your suspicion

The single most useful clue is one-sided, persistent inflammation that does not respond to treatment [1]. If your cat has had the same ear treated repeatedly with cleaners, drops, or antibiotics and the discharge never fully clears, a tumor needs to be ruled out. Chronic inflammation can itself lead to abnormal tissue growth and eventually tumors, so a long history of ear problems does not explain away a mass [1][2].

If your cat has a red, irritated ear that keeps flaring, see Cat Ear Infection with Redness: Causes and When to Worry. If the discharge has been going on for weeks, Cat Ear Infection: Signs and When to See a Vet walks through what to expect at the appointment.

Causes and Risk Factors

The exact cause of ear canal tumors is not known. Several theories exist, and they overlap [2].

Chronic inflammation. Long-term inflammation of the ear canal can lead to hyperplasia (extra cell growth), then dysplasia (abnormal cells), and finally neoplasia (a true tumor) [2]. This is why years of untreated or undertreated ear disease matter.

Bacterial activity in the canal. During episodes of otitis externa, bacteria break down fatty acids and other products in the thickened secretions from overgrown wax glands. This process may contribute to cancer development in the ear canal [2].

Age. Cats over 11 years old are more likely to have malignant ear tumors. The higher rate of malignancy in older cats appears to come from how long the ear disease has been present, not from age by itself [2].

Anatomy. Some cats have narrow or folded ear canals that trap debris and moisture. In one study of external ear masses, several of the affected cats were Maine Coons, though the study was small and this does not prove a breed risk [7].

What does not cause it. There is no evidence in these sources that ear cleaning, ear mite treatment, or diet causes ear cancer in cats.

How Veterinarians Diagnose a Cat Ear Tumor

Physical exam and otoscopy

Your vet starts by looking in the ear with an otoscope. This is often harder than it sounds. A tumor can narrow the ear canal so much that a full view is impossible [3]. Video-otoscopy gives a magnified view and can detect masses that are easy to miss. In one study comparing video-otoscopy with CT, both methods identified the same 13 masses out of 32 ears examined, with perfect agreement between them [7].

Imaging

CT and MRI show the size of the mass, how deep it goes, and whether it has spread into nearby structures such as the salivary glands or lymph nodes [5]. Ultrasound of the ear canal and parotid gland can also help define the size, shape, and extent of a ceruminous tumor [3]. Imaging does not replace a biopsy, but it tells your vet whether surgery is even possible.

Biopsy and histopathology

A tissue sample is the only way to know for certain whether a mass is cancer and what type it is. Samples are usually collected during surgical removal or as a separate biopsy procedure [3]. Histopathology is the main diagnostic tool for identifying the nature of an ear tumor [3].

Staging

If cancer is confirmed, your vet may recommend staging to check whether it has spread. This typically involves imaging of the head and chest and possibly sampling of nearby lymph nodes. Ceruminous gland adenocarcinomas are often locally invasive and can extend into adjacent muscle and lymph nodes [5].

Treatment Options for Cat Ear Cancer

Treatment	What it involves	When it is used
Surgery (TECA)	Total ear canal ablation removes the entire ear canal and often the middle ear	Most common approach for ear canal tumors, especially when the mass is confined to the canal [8]
Surgery plus radiation	Tumor removal followed by radiation therapy	When margins are incomplete or the tumor is aggressive [4]
Radiation alone	Coarse fractionated or palliative radiation	When the tumor is too invasive for surgery [4][5]
Chemotherapy	Systemic drugs, sometimes combined with radiation	Selected cases, often when cancer has spread
Medical management	Ear cleaning, infection control, pain relief	Cats who cannot undergo anesthesia or whose owners decline surgery

Surgery

Total ear canal ablation, often called TECA, is the standard surgical option for tumors inside the ear canal. In a review of 52 TECA procedures in 44 cats, cancer was the reason for surgery in 41 percent of cases, and 86 percent of those cancers were ceruminous gland adenocarcinoma [8]. The same review found that cats with ceruminous gland adenocarcinoma had a median survival time of about 50 months after surgery, which did not differ significantly from cats operated on for inflammatory or polypoid disease [8].

Surgery on the ear flap itself is different. Small tumors on the pinna can sometimes be removed with a wide margin and closed, leaving the canal untouched.

Radiation and chemotherapy

When a tumor has invaded surrounding tissue and cannot be fully removed, radiation therapy can provide palliative benefit, meaning it aims to control the tumor and improve comfort instead of cure [5]. In one case report, a cat with ceruminous gland adenocarcinoma that had invaded the parotid and salivary regions was treated with palliative radiation at 36 Gy delivered in 6 weekly fractions, with CT and MRI used to monitor response [5]. Chemotherapy is used in some cases, often alongside radiation [4].

What about ear polyps?

Not every mass in a cat's ear is cancer. In one study, 9 of 13 external ear masses turned out to be polyps on histopathology [7]. Polyps are benign growths that can cause discharge, head shaking, and odor, and they can look very similar to tumors on exam. Learn more in Ear Polyps in Cats: Signs, Diagnosis, Surgery, and Recurrence.

Recovery, Outlook, and Long-Term Management

What to expect after surgery

TECA is a major operation, and complications are common. In the 52-procedure review, Horner's syndrome occurred in 42 percent of cats and facial paralysis in 56 percent [8]. Horner's syndrome causes a drooping eyelid, a small pupil, and a sunken eye on the operated side. Facial paralysis causes a drooping ear, lip, and eyelid.

The good news is that many of these complications improve. Horner's syndrome was permanent in 14 percent of cases and facial paralysis in 28 percent, with the rest resolving over the following weeks to months [8]. Cats appear to have higher rates of these complications than dogs, likely because the feline nerve structures in that area are more fragile [8].

Outlook

Outlook depends heavily on tumor type, how completely it was removed, and whether it had spread. In one case series of 25 cats with squamous cell carcinoma of the ear canal, middle, or inner ear, cats treated with surgery had a median survival time of 168 days, compared with 85 days for cats treated with medical management [4]. That difference is meaningful, but it also shows that this cancer is serious even with treatment.

For ceruminous gland adenocarcinoma, the mitotic index (a measure of how fast tumor cells are dividing) may help predict outcome. In the TECA review, cases with a mitotic index of 3 or higher appeared to have a worse prognosis [8].

Long-term management

After treatment, most cats need regular rechecks. Your vet will examine the surgical site, check the remaining ear, and may recommend periodic imaging if the tumor was invasive [5]. Keep the remaining ear clean and dry, and report any new discharge, odor, or swelling right away. If your cat has balance problems after surgery or during treatment, see Cat Ear Infection with Loss of Balance: Emergency Signs.

Prevention

There is no proven way to prevent ear cancer in cats. The most practical step is to treat ear disease properly and completely.

Take recurring ear infections seriously. Persistent one-sided inflammation that does not respond to treatment is a reason to look for a tumor, not to try another drop [1].
Finish prescribed ear treatments and keep follow-up appointments.
Ask your vet to look for a mass if your cat has had ear problems for months or years, since chronic inflammation can progress to tumors [2].
Check your cat's ears at home. Look for lumps, sores, discharge, or odor, especially in cats over 11 years old [2].
If your cat has pain when the ear is touched, Cat Ear Infection with Pain: Signs and Emergency Steps covers what to do next.

Limitations and When to Contact a Veterinarian

This article cannot tell you whether your cat has cancer. Only a veterinarian can examine your cat, take a sample, and give you a diagnosis. Individual cases need a veterinarian's assessment.

Contact a veterinarian the same day if your cat has:

A new lump or sore in or on the ear
Bloody or pus-filled discharge from one ear
A foul odor that returns after cleaning
A head tilt, loss of balance, or circling
Facial drooping, a drooping eyelid, or a sunken eye

Seek emergency care now if your cat has:

Sudden collapse or inability to stand
Severe disorientation or seizures
A draining abscess below the ear with swelling that is spreading
Trouble breathing

Schedule a routine visit if your cat has:

A history of ear infections that keep coming back
One ear that always seems to bother her
A mass that has been present for weeks without changing

Frequently Asked Questions

Can a cat ear tumor be mistaken for an ear infection?

Yes, and that is the most common reason diagnosis gets delayed. Tumors cause discharge, odor, head shaking, and scratching, which are the same signs as otitis externa [1]. The clue that separates them is one-sided inflammation that does not respond to standard treatment [1].

Is a lump on a cat's ear always cancer?

No. Benign tumors, inflammatory polyps, and granulomatous tissue can all form masses in the ear [7]. In one study of external ear masses, most turned out to be polyps instead of cancer [7]. A biopsy is the only way to know for sure [3].

What is the most common ear cancer in cats?

Ceruminous gland adenocarcinoma is the most frequently reported malignant tumor of the feline external ear canal [4][5]. It starts in the wax-producing glands that line the canal. Squamous cell carcinoma is more common in the middle ear [4].

Does ear cancer in cats spread?

Some types do. Ceruminous gland adenocarcinomas are often locally invasive and can extend into nearby muscle and lymph nodes [5]. That is why staging with imaging and lymph node checks is often recommended before treatment planning.

Can ear cancer in cats be cured?

Sometimes, if the tumor is caught early and removed completely. Surgery gave cats with one type of ear cancer a median survival of about 50 months in one review, and some cats live longer [8]. When the tumor has spread or cannot be fully removed, treatment focuses on controlling the tumor and keeping your cat comfortable [5]. Your veterinarian will set the plan based on your cat's specific diagnosis, stage, and overall health.

References

Tumors of the Ear Canal in Cats - Cat Owners. Merck Veterinary Manual.
Overview of Tumors of the Ear in Small Animals - Ear Disorders. Merck Veterinary Manual.
Clinical, ultrasonographic and histopathological diagnosis of ceruminous gland tumors in cats. Veterinary research forum : an international quarterly journal, 2021.
Clinical presentation and outcome in cats with aural squamous cell carcinoma: a review of 25 cases (2010-2021). Journal of feline medicine and surgery, 2022.
Case Report: Palliative radiotherapy monitoring using computed tomography and diffusion-weighted magnetic resonance imaging in a cat with ceruminous gland adenocarcinoma. Frontiers in veterinary science, 2025.
Ceruminous gland tumors in dogs and cats: a review of 124 cases. Journal of the American Animal Hospital Association, 1996.
Comparative performance of video-otoscopy and CT in the diagnosis of external ear disease in cats. Journal of feline medicine and surgery, 2024.
Total ear canal ablation in the cat: indications, morbidity and long-term survival. The Journal of small animal practice, 2003.