Squamous Cell Carcinoma (Common in Ears, Nose, and Gums)

ImmunityDiseasesMeongsiljang Veterinary Advisory Board

Squamous cell carcinoma is a malignant tumor that arises from the surface cells of the skin and mucous membranes, commonly occurring in the ears, nose, and gums. Early detection and surgical excision are critical factors in significantly improving survival rates.

What Is Squamous Cell Carcinoma? Key Points

An image of a veterinarian examining a white cat with a red lesion on the tip of its ear.

Squamous cell carcinoma is a malignant tumor that arises from squamous epithelial cells (keratinocytes) lining the skin and mucous membranes. Early detection is crucial. If you notice non-healing ulcers or red lumps on the ear tips, nose, or gums that persist for more than two weeks, immediate veterinary examination is necessary. In cats, these tumors commonly occur on the ear tips and nose (nasal planum), especially in white or lightly pigmented individuals, while in dogs, they most frequently develop in the oral cavity (gums and tongue). Squamous cell carcinoma is the most common oral tumor in cats and the second most common in dogs. Metastasis typically occurs late in the disease course, spreading to lymph nodes and lungs, and the overall metastatic rate is relatively low. However, the tumor is highly locally invasive, and squamous cell carcinoma of the maxilla and tongue in cats carries a poor prognosis, making timely treatment essential.

Causes and Pathogenesis

Squamous cell carcinoma arises when the DNA of squamous epithelial cells (keratinocytes) is damaged, leading to abnormal proliferation. The primary risk factor is exposure to ultraviolet (UV) radiation. Areas with white or lightly pigmented fur, such as the ear tips, nose, and eyelids, have weaker natural protection against UV rays, making cats that frequently sunbathe more susceptible to developing this cancer. UV-induced lesions typically progress slowly to cancer through precursor changes like actinic keratosis, which present as scabs or redness. While papillomavirus antigens have been detected in some feline squamous cell carcinomas, their exact role in the development and progression of the disease remains unclear. Dogs are also at increased risk if their lightly pigmented, sparsely haired skin is repeatedly exposed to UV radiation.

Key Symptoms Checklist (By Location)

Symptoms vary depending on the affected area. If any of the following signs persist for more than two weeks, a veterinary examination is recommended.

Lesions on the ear tips: Common in cats; characterized by recurring scabs and ulcers that are slow to heal.

Nasal (nasal planum) changes: Development of pink nodules, bleeding, or loss of pigmentation.

Gingival or oral masses: Common in dogs; presents as red or white protruding growths, often accompanied by bleeding.

Worsening halitosis: A strong, foul odor is particularly noticeable in oral forms.

Decreased appetite and drooling: Pets may avoid eating due to oral pain.

Toe deformities: Swelling around the nails and nail loss.

A veterinarian examining a puppy's gums.

Signs Requiring Immediate Veterinary Attention

If you notice any of the following signs, your pet may not need emergency care, but a veterinary visit within 24–48 hours is recommended: ① an ulcer that fails to heal for more than three weeks, ② recurrent bleeding from a lump in the mouth, ③ sudden asymmetry of the face or jaw, ④ persistent swelling and pain around the toes or nails, and ⑤ recurring crusts on the ear tips of older white cats. Squamous cell carcinoma is often mistaken for simple inflammation in its early stages, so delaying a biopsy can allow the cancer to metastasize.

Diagnostic Methods - Tissue Biopsy Is Key

A definitive diagnosis of squamous cell carcinoma requires a tissue biopsy. Visual examination alone is insufficient to distinguish it from common inflammation or granulomas. The diagnostic process proceeds as follows:

Fine-needle aspiration (FNA): A primary screening tool that is quick and straightforward.

Punch or incisional biopsy: Tissue is removed for histopathological examination to confirm the diagnosis.

Imaging studies: X-rays and CT scans are used to assess bone invasion and potential metastasis.

Thoracic and lymph node evaluation: Screening for lung metastasis and regional lymph node involvement.

Treatment Options - Approaches by Location and Stage

The first-line treatment is complete surgical excision. Removing a wide margin of healthy tissue surrounding the tumor helps lower the recurrence rate. Treatment strategies vary by location as follows: Pinna squamous cell carcinoma (cats): Pinnectomy (surgical removal of the ear tip); prognosis is favorable in early stages. Nasal squamous cell carcinoma: Nasal resection or radiation therapy; complete excision may be challenging due to the location. Oral form (dogs): Partial mandibulectomy or maxillectomy, supplemented with radiation and chemotherapy. Digital form: Digit amputation. Your veterinarian will determine the optimal combination of treatments based on the disease stage and the patient’s overall condition.

A scene of preparing for veterinary surgery

Comparison of Characteristics by Affected Site

Item	Ear-tip type (cats)	Oral type (dogs)	Toe/digit type
Main affected group	Older cats with white fur and little pigment	Older dogs (the second most common oral tumor)	Older animals (digital involvement also reported in cats)
Rate of progression	Slow (actinic keratosis → cancer over time)	Can be locally rapid	Variable
Metastasis risk	Low (mainly local invasion)	Usually late (to lymph nodes and lungs after disease progression)	Metastasis possible if poorly differentiated
First-line treatment	Ear-tip amputation	Wide excision + radiation	Digit amputation
Prognosis with early detection	Good	Intermediate (poor for maxillary and lingual types)	Good

Actual prognosis varies depending on tumor size, metastasis, and patient condition

Home Care and Management Tips

Post-operative home care is crucial for preventing recurrence. Keep the Elizabethan collar on for at least two weeks to prevent your pet from licking the surgical site, and administer prescribed antibiotics and pain relievers at the scheduled times. Sun protection is essential. For white-coated cats, minimize sunbathing near windows and limit outdoor time to early morning and evening. For patients with oral issues, switch to a soft prescription wet food to reduce chewing discomfort. Make it a habit to check the surgical site, as well as the opposite ear, nose, and gums, every week.

A guardian caring for a white cat wearing an Elizabethan collar

Breed-Specific and Individual Precautions

White cats with little pigment are especially prone to squamous cell carcinoma on sun-exposed areas like the tips of their ears, nose (nasal planum), and eyelids. Textbooks identify “low-pigment, sparsely haired skin plus strong, repeated UV exposure” as the key risk factors, and no clear breed predisposition has been reported in either dogs or cats. Dogs with lightly pigmented skin are also at increased risk if exposed to sunlight repeatedly over time. Even after successful treatment, the condition can recur or appear in new areas if UV exposure and chronic irritation persist, so a full-body skin and oral exam every six months is recommended.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Is squamous cell carcinoma contagious?

No, squamous cell carcinoma is not contagious to humans or other pets. It is a malignant tumor that develops due to a combination of environmental factors, such as exposure to ultraviolet light, and individual factors, such as skin with low pigmentation.

Can it be treated with radiation or medication alone, without surgery?

Treatment depends on the tumor’s location and stage, but primary treatment usually involves surgical removal. If the tumor is in a difficult-to-reach area or if anesthesia is risky due to advanced age or underlying health conditions, radiation or chemotherapy may be used as alternatives or adjuncts. Work closely with your veterinarian to determine the best treatment plan.

What is the cure rate after surgery?

The prognosis varies significantly depending on the tumor’s location, stage, and degree of cellular differentiation. In early-stage feline auricular squamous cell carcinoma, complete surgical excision generally yields a favorable prognosis. However, for oral squamous cell carcinoma in cats, tumors located on the maxilla (upper jaw) or tongue carry a poorer prognosis, whereas those on the mandible (lower jaw) tend to have a comparatively better outlook. Cutaneous forms typically have a low rate of metastasis, but poorly differentiated tumors can spread to the lymph nodes and lungs. To determine an accurate prognosis, please consult your veterinarian after reviewing the results of a histopathological examination and imaging studies.

Is it okay to apply sunscreen?

There are sunscreens specifically formulated for pets. Human sunscreens may contain toxic ingredients such as zinc oxide and parabens, which can be dangerous if ingested. Always use a pet-specific product recommended by your veterinarian, and supervise your pet until the sunscreen is completely dry to prevent licking.

What can I do to help prevent the condition from coming back?

Minimizing UV exposure (keep white-coated cats indoors), maintaining oral hygiene (regular dental cleanings), and scheduling regular check-ups (every six months) are key. Be sure to examine not only the previously affected area but also the opposite side and similar areas.

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References

[1] Withrow & MacEwen's Small Animal Clinical Oncology, 6th Edition - Chapter on Cutaneous and Subcutaneous Tumors

[2] BSAVA Manual of Canine and Feline Dermatology, 4th Edition - Epithelial Tumors Chapter

[3] Veterinary Surgical Oncology, 2nd Edition - Oral and Cutaneous Tumors