Melanoma is a type of cancer originating from melanocytes, specialized cells responsible for producing pigment in the skin, hair, and eyes. While a significant concern in human health, cats can also develop this condition, though it is relatively uncommon compared to other feline cancers or its prevalence in humans.
Feline Melanoma Explained
Feline melanoma involves the uncontrolled growth of abnormal melanocytes. This cancer can manifest in various locations throughout a cat’s body. Oral melanoma, occurring in the mouth, is among the most frequently observed forms, alongside ocular melanoma affecting the eyes, and cutaneous melanoma impacting the skin. Melanoma can also appear on the digits, known as ungual or digital melanoma.
These tumors can be classified as either benign (melanocytoma) or malignant. Malignant melanoma is aggressive and can spread to other parts of the body, a process called metastasis. Unlike human melanoma, feline melanoma is not typically linked to sun exposure as a primary cause, though genetic factors likely play a role in predisposing some cats to this condition.
Recognizing Signs of Melanoma
Identifying the signs of melanoma in cats often depends on the tumor’s location. Oral melanoma may present as dark, raised masses on the gums, tongue, or lips. Cats with oral tumors might exhibit symptoms such as excessive drooling, difficulty eating, or unusually bad breath.
Ocular melanoma, affecting the eye, typically involves changes in eye color, the appearance of dark spots on the iris, or alterations in pupil shape. These changes might begin as small, flat, darkened areas on the iris that gradually enlarge and become raised. Advanced ocular melanomas can lead to a cloudy eye appearance, increased pressure within the eyeball, or even blindness.
Cutaneous melanoma, found on the skin, can appear as dark, often black or brown, raised lumps or masses. While usually pigmented, some skin melanomas may lack pigment. These lesions can sometimes ulcerate and bleed, and are commonly found on the head, ears, or paws.
For ungual melanoma, which affects the nail bed, signs may include lameness, swelling of a digit, or changes around the nail. Any new or changing dark spots or growths warrant a veterinary examination.
Veterinary Diagnosis and Treatment
To diagnose melanoma, a veterinarian performs a fine needle aspiration (FNA) or biopsy of the mass. These samples are analyzed microscopically to determine if cells are cancerous and if the tumor is benign or malignant.
Further diagnostic imaging, such as X-rays, ultrasound, or CT scans, may be recommended to check for metastasis to regional lymph nodes, lungs, or other organs. This staging process determines disease extent and guides treatment. Surgical removal is often the primary treatment for localized melanomas, aiming to remove the entire tumor with clean margins.
Other treatment modalities depend on the tumor’s type, location, and stage. Radiation therapy can be used for tumors challenging to remove surgically or if cancer cells remain. Chemotherapy may be considered if the cancer has spread or is highly aggressive. Immunotherapy, including specific melanoma vaccines, may also be used to stimulate the cat’s immune system against cancer cells.
Outlook and Ongoing Management
The prognosis for cats with melanoma varies considerably based on tumor location, size, and whether it has spread (metastasis). Benign skin melanomas generally have a favorable prognosis, often curable with complete surgical removal. However, malignant oral melanoma often has a guarded to poor prognosis due to its aggressive nature and high potential for metastasis to lymph nodes, lungs, or liver.
Ocular melanomas also have variable outcomes; diffuse iris melanomas are usually malignant and can spread. However, early detection and surgical removal of the eye (enucleation) can improve survival times. Regular follow-up veterinary appointments are important after treatment to monitor for recurrence or new tumor development. Ongoing supportive care focuses on maintaining the cat’s comfort and quality of life.