Cancer in Cats: Symptoms and Treatment

Cancer is one word no pet parent wants to hear, but if caught early enough, it can be treatable. In this blog, we are going to discuss different types of cancer in cats, symptoms to be on the lookout for, and how it can be treated if they are diagnosed.

Common Cancers in Cats

The symptoms and treatment of cancer in all animals depend on the type of cancer and how advanced it is. Let us look at some more common feline cancers, their symptoms, and their treatments.

Small Cell Gastrointestinal (GI) Lymphoma

Small Cell Gastrointestinal (GI) Lymphoma is a lymphatic system cancer. Small cell lymphocytes (as opposed to large cell lymphocytes seen in large cell gastrointestinal lymphoma) characterize small cell gastrointestinal lymphoma.

Symptoms: Symptoms of small cell gastrointestinal lymphoma include weight loss, diarrhea, change in appetite, vomiting, and a possible intestinal or abdominal mass.

Treatment: Treatment for small cell gastrointestinal lymphoma in cats consists of oral steroids and chemotherapy.

Prognosis: Under the treatment above, 90% of cats experience symptom remission and have a prognosis of two to three years.

Oral Squamous Cell Carcinoma

In oral squamous cell carcinoma, the cells that line the oral cavity and protect underlying tissue become cancerous. The most common type of oral cancer in cats is oral squamous cell carcinoma.

Symptoms: Symptoms of oral squamous cell carcinoma include oral inflammation, dental disease, mouth lesions, loose teeth, and oral ulceration.

Treatment: Treatment for oral squamous cell carcinoma is the surgical removal of the lesion-affected tissue and (in the case of shallow lesions) radiation therapy. Oral squamous cell carcinoma is also treatable with cryotherapy if it is caught early enough.

Prognosis: The prognosis for feline oral squamous cell carcinoma is poor – between 2 to 4 months – but this depends on the location, size, and whether the tumor has metastasized.

Feline Leukemia Virus (FeLV)

Although we know leukemia as cancer, FeLV or Feline Leukemia Virus is a virus in cats that causes changes in DNA through viral replication within cells. Approximately 30% of cats infected with this virus successfully fight off the infection, but in cats that cannot fight infection, it can cause a weakened immune system and makes a cat more susceptible to more severe illness and cancer. FeLV passes through an infected cat’s body secretions (most often after prolonged exposure.) Approximately 40% of infected cats will develop progressive FeLV.

Symptoms: Feline leukemia virus symptoms include weight loss, diarrhea, fever, anorexia, cancer, infertility, seizures, and poor coat health.

Treatment: There is a vaccination for FeLV, but it is only helpful for cats before infection with the virus, and it is not 100% effective. There is no cure for FeLV in infected cats, and veterinary care centers on treating symptoms.

Prognosis: Of cats diagnosed with FeLV, around 85% succumb to the virus within three to four years.

Skin Cancer or Squamous Cell Carcinoma

Squamous Cell Carcinoma is a cancer of the skin cells. This type of cancer is seen predominantly in white cats (due to a lack of pigment) on their ears and heads. This cancer results from excessive sun exposure and most commonly occurs in older cats.

Symptoms: Symptoms of skin cancer in cats include scabbing on the ears, nose, or head, skin irritation or redness, and hair loss.

Treatment: The preferred treatment for feline squamous cell carcinoma in cats is surgery to remove the affected skin.

Prognosis: Caught in the early stages, Squamous Cell Carcinoma in cats is treatable and relatively harmless. If the skin cancer metastasizes, however, a cat’s prognosis can be much grimmer.

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Mammary Cancer

Feline mammary or breast cancer is usually not seen until late adulthood and is most often aggressive. The treatment outcome of feline breast cancer depends on how early it was caught. Male cats, like human males, can also develop breast cancer, but it is far less common.

Symptoms: Symptoms of mammary cancer in cats include a mass in the abdomen along the mammary chain, weight loss, ulceration of the skin, skin infection, unusual breast discharge, and fever.

Treatment: The chance of mammary cancer in cats significantly reduces by spaying younger cats. Treatment of feline breast cancer is dependent upon the type of cancer discovered. Surgery (followed by chemotherapy if necessary) is the most common treatment for feline mammary tumors.

Prognosis: Mammary cancer is aggressive and likely to return even with complete removal of the infected tissue. Mammary cancer treatment success depends on the type and size of the tumor and whether it has metastasized.


Fibrosarcoma is the most common cause of oral tumors in cats, second only to oral squamous cell carcinoma, but this type of cancer can cause tumors anywhere in the body. This type of tumor is also sometimes seen at vaccination sites, in association with site trauma, or as the result of viral infection.

Symptoms: Symptoms of fibrosarcoma in cats include lumps under the skin, swelling, weight loss, and possible skin ulceration.

Treatment: Treatment for fibrosarcoma depends on where the tumor is, how large it is, and whether it has metastasized. A fibrosarcoma tumor is most surgically removed, with radiation or chemotherapy after removal. Sometimes chemotherapy is necessary to shrink the tumor prior to removal. Tumor removal can be difficult with fibrosarcoma because tumors often develop “tentacles” that get left behind upon removal.

Prognosis: The prognosis for feline fibrosarcoma is poor, with an average survival rate of two to four years for cats that undergo a combination of therapies.


A feline cancer diagnosis is not necessarily terminal but immediate veterinary attention is crucial. If you suspect your cat has signs or symptoms of cancer, or if they have already received a diagnosis, the priority should always be immediate treatment. If you have questions about your cat’s diagnosis, contact your veterinarian and make an appointment where you can get clear answers and be sure to write them down!

If you have any questions about cancer in cats, please call us at (262) 658-3533 or schedule an appointment online!