CONDITION
Squamous Cell Carcinoma
Squamous cell carcinoma is a cancer that arises from the flat, scale-like cells of the skin and of linings such as the mouth. This page covers the skin form in cats, which mostly affects lightly pigmented, sparsely haired skin exposed to sun: the ear tips, nose and eyelids. It tends to begin as a small, persistent change in one place and grow slowly and locally, often appearing as a thickened patch, a non-healing sore, or an area that bleeds easily. Squamous cell carcinoma inside the mouth of cats behaves far more aggressively, with a much poorer outlook, and is covered on its own page. Owners often notice a scab or crust on an ear tip that keeps returning, a raw area on the nose that does not heal, or redness and crusting at the eyelid edge. Early changes can be subtle and are easily mistaken for a fight wound, infection or minor injury. This page explores what an owner may observe, what is happening at the tissue level, how the diagnosis is confirmed, and the range of approaches that may be considered depending on the site, the extent of local involvement, and whether spread has occurred.
Why this matters now
Squamous cell carcinoma is a malignant skin cancer commonly affecting cats, with particular predilection for areas with minimal fur cover and light pigmentation. The ear tips, nose, and eyelids of white or light-coloured cats are most frequently affected due to sun exposure. The tumour is locally aggressive, gradually destroying surrounding tissue. Unlike some other feline cancers, squamous cell carcinoma tends to spread locally rather than to distant organs, though advanced cases can metastasise.
The condition often begins with subtle changes: crusting, scabbing, or non-healing wounds on the ears or nose. These early lesions may be mistaken for fight wounds or minor irritation. Without intervention, the tumour progressively invades deeper tissues, causing significant tissue destruction. Ear tip lesions may erode through the pinna. Nasal lesions can extend into the nasal cavity, causing breathing difficulty and disfigurement. Small lesions found early are more often curable than advanced ones.
Signals & patterns
Early signals
Crusting or scabbing on ear tips
Persistent crusty lesions that do not heal with time or topical treatment.
Non-healing wound on the nose
A sore or ulcer on the nasal planum that recurs or fails to resolve.
Redness and thickening of skin
Pre-cancerous changes may appear as chronic inflammation of sun-exposed areas.
Changes around the eyes
Crusting or ulceration of the eyelid margins in light-coloured cats.
Later signals
Tissue erosion
Progressive destruction of ear or nose tissue becomes apparent as the tumour advances.
Bleeding from affected areas
Ulcerated tumours may bleed, sometimes significantly.
Difficulty breathing
Nasal tumours extending into the nasal passages cause obstruction and noisy breathing.
Facial deformity
Advanced nasal or periocular tumours cause visible distortion of facial features.
Click to read about the biological mechanisms
How this is usually investigated
Diagnosis involves examining suspicious lesions and obtaining tissue samples. Staging assesses local extent and checks for spread.
Physical examination
Biopsy
Fine needle aspirate of lymph nodes
CT scan
Chest radiographs
Options & trade-offs
Treatment options depend on tumour location, size, and extent. Early lesions often have good outcomes; advanced tumours are more challenging.
Surgical excision
Removing the tumour with margins of healthy tissue.
Trade-offs: Curative for many early lesions. Ear tip amputation (pinnectomy) is well tolerated and often curative for ear tumours. Nasal planum removal is more disfiguring but can control disease.
Cryotherapy
Freezing small superficial tumours with liquid nitrogen.
Trade-offs: Suitable for very early or pre-cancerous lesions. Less invasive than surgery. May require multiple treatments. Not appropriate for invasive tumours.
Radiation therapy
Using radiation to kill cancer cells.
Trade-offs: Effective for tumours where surgery is difficult or incomplete. External beam radiotherapy is given in several sessions, each under anaesthesia; superficial lesions can be treated with strontium-90 plesiotherapy, a contact technique often given as a single session. Side effects can occur in irradiated tissue.
Photodynamic therapy
A specialised treatment combining a light-sensitive drug with specific light wavelengths.
Trade-offs: Available at some referral centres. Suitable for superficial tumours. Afterwards, the cat is kept out of sunlight for at least two weeks.
Sun avoidance
Keeping cats indoors during peak UV hours and using pet-safe sunscreen.
Trade-offs: Important for prevention and may slow progression of early changes. Does not treat established tumours but helps prevent new ones.
Common misconceptions
"Indoor cats cannot get sun-related skin cancer"
Cats that sunbathe by windows still receive UV exposure. Glass blocks some but not all UV radiation. Indoor cats with light colouring can develop squamous cell carcinoma.
"A crusty ear tip will heal on its own"
Early squamous cell carcinoma on the ear tips or nose of white cats can look like a minor scab or wound, but it does not resolve and gradually worsens.
"Surgery will leave my cat disfigured and unable to cope"
Cats adapt remarkably well to ear tip removal. Nasal surgery, whilst changing appearance, is generally well tolerated. Cats prioritise comfort over aesthetics.
Related conditions
Squamous Cell Carcinoma of the Nasal Planum
Squamous cell carcinoma of the nasal planum is a site-specific form of the same cancer type, arising in the nose leather rather than other skin or mucosal surfaces. The underlying cellular origin and behaviour are shared, though the anatomical location shapes what an owner may observe and which approaches may be considered.
Squamous Cell Carcinoma of the Pinna in Cats
Squamous cell carcinoma of the pinna represents the same tumour type occurring on the ear flap, often in response to chronic sun exposure in lightly pigmented cats. The mechanism of sun-induced cell damage and the progression from precancerous change to invasive growth are common to both conditions.
Oral Squamous Cell Carcinoma in Cats
Oral squamous cell carcinoma in cats arises from the same cell type as squamous cell carcinoma elsewhere, but occurs within the mouth and tends to behave more aggressively in that location. The distinction lies in site and pattern of local invasion, rather than the fundamental nature of the cancer.
Oral Melanoma
Oral melanoma can appear in similar locations within the mouth as squamous cell carcinoma, and both may present as masses or non-healing sores that affect eating. The two are distinct cancer types with different cellular origins, but can be part of the differential diagnosis when a growth is found in the oral cavity.
Mast Cell Tumours in Cats
Mast cell tumours in cats are another skin tumour, arising from a different cell type and behaving differently. Both can appear as skin lumps or sores, and a sample is needed to tell them apart from each other and from benign growths.
Being aware that white or light-coloured cats face higher risk helps target monitoring efforts. Checking ear tips and nose regularly for changes allows early detection. Understanding that early lesions are often curable encourages prompt investigation of suspicious changes. Taking steps to reduce sun exposure may help prevent disease development.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS