Skin and Toe Cancer in Cats

Several types of skin cancer can affect the toes as well; these include soft tissue sarcoma, fibrosarcoma, and squamous cell carcinoma. A rare type of cancer called feline lung-digit syndrome may also cause tumors to appear on the toes or feet.

Skin tumors are some of the most commonly identified tumors in cats, primarily because the skin is particularly susceptible to carcinogens present in the environment. Cats with white skin and fur have a predisposition for developing skin cancer.

Since there are many types of skin conditions that may cause lesions or discolored patches, identifying a lesion as cancer can only be done by a veterinarian. However, if you notice any of the following symptoms, contact your vet immediately:

• Signs of pain when walking
• Lameness
• Lethargy or weakness
• Masses located on the toes or footpads
• Swollen or inflamed paws
• Blisters 
• Draining or bleeding sores
• Excessive grooming of the paws
• Tumors located on other parts of the body
• Discharge from the nail bed
• Coughing up blood
• Loss of appetite
• Weight loss
• Rapid or labored breathing

Types

Malignant cancer, no matter where it originates, has the potential to spread to any part of the body, including the toes. There are several different types of skin cancer, and these can also affect any part of the body. The types discussed here primarily affect a cat’s digits (toes).

Soft Tissue Sarcoma

This type of skin cancer, most commonly found in other areas of a cat’s body, develops in the stem cells. Older cats have a predisposition for developing digital soft tissue sarcoma. This condition, when found in the toes, will usually only affect one digit, and has a high rate of recurrence. At present, metastasis has not been observed, unless the sarcoma is located within the deep tissue. Malignancy seems to correspond with tumor size.

Digital Fibrosarcoma

Similar to soft tissue sarcoma, fibrosarcoma affects the soft tissue of a cat, and may develop anywhere on the body. Fibrosarcoma originates in fibroblasts, which are cells located within the connective tissue that produce collagen. There are three main types of fibrosarcoma, and each has different causes. One type of fibrosarcoma may originate in younger cats from the feline sarcoma virus. Fibrosarcomas may also develop in vaccination sites. And finally, the more common type of fibrosarcoma affects older cats and has no identifiable underlying cause.

Squamous Cell Carcinoma

SCC, while relatively common in cats, only rarely affects the cat’s digits. This is because this kind of tumor generally forms in areas that have less pigmentation, such as the ears, nose, and head. Before a tumor forms, cats will show signs of solar keratosis, in which the skin becomes discolored or thick. Preventative measures for SCC primarily involve limiting the cat’s exposure to ultraviolet light.

Feline Lung-Digit Syndrome

Feline Lung-Digit Syndrome is a type of rare pulmonary cancer that has a strange metastatic pattern. Though the cancer originates in the lungs, tumors will form on the toes and limbs. These tumors can affect multiple toes and limbs. By the time tumors appear on the skin, the lung cancer has usually progressed, and the prognosis is poor.

As with most cancers, the causes of skin and toe cancer in cats are not fully understood. However, there are some factors that increase a cat’s likelihood of developing skin cancer. Cats with white fur have a higher chance of developing skin cancer due to a lack of pigmentation. This makes it easier for UV light to penetrate and cause cancer.

Fibrosarcoma has more identifiable causes, from vaccinations – particularly in cats receiving rabies and FeLV injections – to viruses. However, in most forms of fibrosarcoma that affect the toes, there is no identifiable cause.

Your vet will be able to make a tentative diagnosis based on the appearance of the paws and presentation of symptoms. You should be prepared to provide the vet with the extent and duration of your cat’s symptoms, a summary of your cat’s outdoor activity, and a complete medical history.

The vet can use a number of tests to make a definitive diagnosis, including microscopic examination, blood analysis and chemical profile, and a biopsy of the tumor. The vet will also conduct tests for lung cancer at this time, including x-rays, CT scans, fine needle aspiration, and fluid analysis.

Treatment will depend on the underlying cause of the cancer. Surgery is usually the recommended course of treatment, with some cases resulting in amputation of the affected toe. With sarcomas, recurrence is common even with surgical treatment. Radiation treatment and chemotherapy may also be recommended following surgery to ensure that the tumors have been eradicated as well as possible. In situations where tumors cannot be physically removed, chemotherapy is the general course of treatment. 

For Feline Lung-Digit Syndrome as well as other types of lung cancer, treatment is usually palliative as mortality rates are high given the late stage of the cancer. Recurrence rate is also high, and pulmonary cancer tends to resist drug therapy.

Pain management medication and other drugs may also be prescribed to help manage your cat’s symptoms or stimulate appetite, particularly if it is receiving chemotherapeutic treatment. Your vet will be able to customize a treatment plan based on your cat’s specific needs.

Always follow your vet’s instructions carefully regarding postoperative treatment. Depending on the type of cancer involved, your cat may be hospitalized for a short time following surgery to recover and rest.

On the return home, ensure your cat has a safe, warm place to rest. Always administer medications according to your vet’s explicit instructions. Do not let your cat outside during the recovery period, as exposure to sunlight and the environment may cause complications or recurrence.

If the tumors recur, contact your vet immediately.