CONDITION
Ceruminous Gland Tumours in Dogs and Cats
Ceruminous gland tumours are growths that arise from the wax-producing glands lining the ear canal. These glands normally produce a secretion that combines with sebum to form earwax; when cells in these glands begin to grow abnormally, they can form either benign tumours (adenomas) or malignant ones (adenocarcinomas). Whilst uncommon overall, ceruminous gland tumours are the most frequently encountered ear canal tumours in dogs, and one of the most common malignant ear tumours in cats. Malignant tumours are found more often than benign ones in both species. In one large study of ear canal tumours, about 6 in 10 dogs and nearly 9 in 10 cats had a malignant tumour. Some owners notice a mass inside the ear canal during grooming, but the tumour more often comes to light after signs such as head shaking, discharge or odour, and the mass is often seen only when the ear canal is examined with an otoscope. The growth may be visible as a pink, reddened, or ulcerated lump, and in some cases the ear canal can become narrowed or blocked. Chronic ear inflammation or recurrent infections can sometimes precede the appearance of a tumour, though the relationship between inflammation and tumour development remains an area of ongoing investigation. This page explores the signs that may bring a ceruminous gland tumour to attention, what is understood about how these tumours develop and behave, the investigations used to characterise them, and the range of approaches that exist for managing them. The distinction between benign and malignant forms, and the extent of local involvement, tends to shape the course and options available.
Why this matters now
Ceruminous gland tumours tend to appear in middle-aged to older animals, with an average age around nine to ten years in both dogs and cats. Cocker spaniels and poodles may be seen more frequently with these tumours, though they can arise in any breed or in mixed-breed animals. Some reports suggest benign ear canal tumours are seen more often in middle-aged animals and malignant ones in animals over about 11 years old, but studies do not agree on this.
The course can vary considerably depending on whether the tumour is benign or malignant. Benign adenomas may grow slowly to a certain size and remain stable, sometimes causing little disruption if they do not obstruct the canal. Malignant adenocarcinomas tend to be locally aggressive, often invading surrounding tissue including the cartilage of the ear canal, and sometimes the bone around the middle ear. In some cases they spread to nearby lymph nodes or, more rarely, to distant organs such as the lungs. Many malignant tumours ulcerate and become a focus for persistent infection, which can complicate the picture over time.
Signals & patterns
Early signals
Persistent ear discharge
An owner may notice discharge that is waxy, thick, or occasionally tinged with blood, often in greater volume than would be typical with a straightforward ear infection. The discharge may have an unpleasant odour and can recur despite routine cleaning.
Head shaking or ear scratching
The dog or cat may shake their head repeatedly or paw at the affected ear, behaviours that reflect irritation or discomfort within the canal. These signs can sometimes be mistaken for a simple ear infection, particularly if they come and go.
Visible mass in the ear canal
During grooming or examination, a pink, reddened, or fleshy lump may be seen inside the ear canal. The growth can vary in size and may appear smooth or irregular, and in some cases it may partially obstruct the canal opening.
Recurrent ear inflammation
The ear may become inflamed repeatedly, with redness, warmth, and swelling that does not fully resolve between episodes. This pattern can precede the recognition of a tumour, though the relationship between chronic inflammation and tumour development is not entirely clear.
Later signals
Head tilt or loss of balance
If the tumour extends deeper into the middle or inner ear, the dog or cat may hold their head tilted to one side, walk in circles, or appear unsteady. These signs reflect involvement of structures that govern balance and spatial orientation.
Facial asymmetry or drooping
Invasion of nearby nerves can lead to drooping of the lip or ear on the affected side, with difficulty blinking or eating, when the tumour affects the facial nerve as it passes near the ear canal. Tumour in the middle ear can also cause Horner's syndrome, with a droopy eyelid and a small pupil on that side.
Swelling around the ear base
A firm swelling may develop near the base of the ear if the tumour grows beyond the canal, and it may continue to enlarge. Separately, vigorous head shaking can cause a soft, blood-filled swelling in the ear flap (an aural haematoma).
Click to read about the biological mechanisms
How this is usually investigated
Investigation typically begins with a thorough examination of the ear canal, often using an otoscope to visualise the mass and assess its size, location, and appearance. The history of ear infections, discharge, or changes in behaviour helps to build context. As the picture develops, sampling the tissue and imaging the surrounding structures allow the clinical team to distinguish benign from malignant forms and to map the extent of any local involvement.
Physical examination
Cytology
Histopathology
Computed tomography (CT)
Lymph node cytology
Options & trade-offs
Management is shaped by whether the tumour is benign or malignant, the extent of local invasion, and the practical considerations facing the individual animal and owner. Approaches often combine local control of the tumour with management of secondary infection and discomfort. Different animals and households find different combinations workable, and the picture may evolve over time as the tumour's behaviour becomes clearer.
Surgical resection
Removal of the tumour can range from excision of a small, pedunculated mass to total ear canal ablation combined with lateral bulla osteotomy when the tumour is extensive or has invaded the canal wall and middle ear. The procedure aims to achieve clear margins around the tumour and to address any infection or debris within the canal and bulla. In many cases, surgical removal gives good long-term local control.
Trade-offs: Total ear canal ablation is a substantial procedure that permanently removes the external canal and typically results in loss of hearing on that side; complications can include infection, nerve damage affecting facial movement, and a prolonged recovery. Less extensive surgery may leave residual tumour if margins are incomplete, and benign lesions may recur if not fully excised.
Radiation therapy
External-beam radiation can be used after incomplete surgical excision to target residual tumour cells, or as a primary treatment when surgery is not feasible due to the tumour's location or the animal's health. A course of fractionated radiation is delivered over several weeks, aiming to damage tumour cells whilst limiting harm to surrounding normal tissue.
Trade-offs: Radiation requires repeated general anaesthesia for each fraction and access to a specialist oncology centre. Acute side effects can include inflammation of the skin and ear canal, whilst late effects may involve fibrosis or changes in bone and soft tissue; radiation does not eliminate all tumour cells in every case, and response can vary.
Medical management of secondary infection and inflammation
Many ceruminous gland tumours, particularly malignant ones, become ulcerated and harbour bacterial or yeast infections that contribute to discharge, odour, and discomfort. Topical or systemic antimicrobials, along with anti-inflammatory medication, can reduce these signs and improve the animal's day-to-day comfort, even when the tumour itself is not being directly treated.
Trade-offs: Medical management addresses the consequences of the tumour rather than the growth itself, and signs often recur once treatment is paused. This approach may be suitable when surgery or radiation are declined or not feasible, but it does not alter the tumour's progression.
Monitoring without active intervention
Some small, benign adenomas grow slowly and cause minimal obstruction or discomfort, and may be observed over time with periodic examinations. This approach allows the owner and clinical team to track any change in size, appearance, or associated signs before deciding whether intervention is needed.
Trade-offs: Monitoring is only appropriate when the tumour is causing little disruption and the risk of rapid progression appears low. Distinguishing a truly indolent mass from one that will later become problematic requires careful follow-up, and any change in behaviour, discharge, or comfort may prompt a shift to active treatment.
Common misconceptions
"A tumour in the ear canal can be cured with ear drops or antibiotics."
Ear drops and antibiotics can manage secondary infection and reduce discharge or odour, but they do not remove or shrink the tumour itself. The growth remains and may continue to enlarge, narrow the canal, or invade surrounding tissue regardless of medical treatment for infection.
"If the lump is benign, it will never cause problems."
Benign adenomas can still obstruct the ear canal, trap debris and moisture, and create a focus for recurrent infection. Some grow large enough to cause discomfort or affect hearing, and incomplete surgical removal can lead to regrowth over time.
"Surgery for ear canal tumours is always disfiguring and leaves the animal deaf."
The extent of surgery depends on the size and invasiveness of the tumour. Small, accessible growths may be removed with preservation of the canal and hearing, whilst more extensive disease may require total ear canal ablation, which does result in hearing loss on that side. Many animals adapt well to hearing loss on one side. Nerve problems after this surgery are common, even with careful technique. In one study of dogs and cats, about half of operated ears had some facial nerve weakness or paralysis afterwards, which usually lasted a few weeks. Cats are more likely than dogs to develop Horner's syndrome (a droopy eyelid and small pupil) and lasting facial nerve problems. In a UK series of cats, facial paralysis occurred in 56% of cases and Horner's syndrome in 42%; these stayed permanent in 28% and 14% of cases.
Related conditions
Ear Mites
Ear mites can cause chronic irritation and inflammation in the ear canal, and whilst the relationship between long-standing inflammation and tumour development remains an area of investigation, persistent parasitic infection may contribute to the inflammatory environment in which ceruminous gland tumours occasionally arise. Both conditions can produce discharge and head shaking, though ear mite infestations typically appear earlier in life and respond to anti-parasitic treatment.
Cutaneous Lymphoma
Cutaneous lymphoma can occasionally involve the skin of the ear canal, presenting as masses or ulcerated lesions that may resemble ceruminous gland tumours on initial examination. Distinguishing between these requires biopsy, as the behaviour, treatment approach, and prognosis differ considerably between a ceruminous gland adenocarcinoma and lymphoma affecting the same site.
Anal Sac Adenocarcinoma
Both can invade nearby tissue and can spread to nearby lymph nodes. Ceruminous gland adenocarcinoma spreads less often. In one large study, most dogs with a malignant ear canal tumour lived longer than two years. Both arise from apocrine glands, so the principles of staging, surgical planning and follow-up often overlap.
Brain Tumours
In cases where a ceruminous gland tumour erodes through the bone of the ear canal or spreads into surrounding structures, it can extend towards the skull base and affect nearby nerves, producing signs that may overlap with those seen in animals with brain tumours, such as head tilt, balance changes or facial nerve involvement. This extension influences both the feasibility of surgical removal and the range of signs an owner may observe.
Otitis Externa in Dogs
Chronic ear inflammation, sometimes driven by allergies or recurring infections, can precede the development of ceruminous gland tumours in some animals, and owners may notice persistent ear discharge or discomfort before a growth becomes visible. Both conditions can present with similar signs, such as head shaking, discharge and ear irritation, so it is useful to distinguish ongoing inflammation from an emerging mass.
Otitis Externa in Cats
Otitis externa in cats can produce the same head shaking, discharge and ear irritation as an ear canal tumour, and a tumour often carries a secondary infection, so the two can be present together.
Understanding the distinction between benign and malignant forms, and the extent of local involvement, can help shape conversations about what might be feasible and what trade-offs different approaches carry. The relationship between chronic ear inflammation and tumour development remains an area of interest, and managing recurrent ear infections in older animals may be a useful conversation in its own right. The longevity and healthspan pillar explores other conditions that tend to emerge in middle-aged and older animals, and the ways in which different layers of care intersect over time.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS