Cat Cancer: Causes, Symptoms, Treatment + Vet Q&A

Cat cancer is a leading cause of death in older cats (senior cats), and its prevalence increases with age. Approximately 1 in 5 cats over the age of 15 may develop cancer.

However, modern treatment and early detection have a great impact on the quality and duration of a cat’s life. 

I will talk about common cancers, their symptoms, and treatment options to help you navigate this devastating disease.

Let’s start.

Cat CancerSymptomsLife Expectancy 
Mammary Gland CancerSwollen or Enlarged Mammary Glands
Ulceration or Open Wounds
Changes in Nipple Appearance
Grade I tumor offers a good one-year survival chance, depending on its size and type.
Grade II tumors show a 57% survival rate with surgery plus chemotherapy.
LymphomaEnlarged Lymph Nodes
Pale Gums
Respiratory Distress
With chemotherapy, around 75% of cats experience remission, and the median survival time increases to six to 12 months.
Chemotherapy significantly improves the outlook for feline lymphoma patients, extending their lifespan and quality of life
Squamous Cell CarcinomaUlcerated or Non-Healing Sores
Raised or Crusty Lesions
Red or Inflamed Areas
Nasal Discharge or Breathing Difficulties

Whether treated with surgery, chemotherapy, or radiation therapy, the survival time is approximately 2-4 months, with less than 10% of cats surviving beyond one year after diagnosis.
Unfortunately, the available treatments do not significantly extend the lifespan of cats affected by this aggressive form of cancer
Bone cancerLameness
Decreased Appetite and Activity
Cats typically have an average survival rate of 12 months, while for axial OSA, the average survival rate is around six months, regardless of the treatment type.
However, cats that undergo amputation as part of their treatment have a significantly improved average survival rate of about four years.
Amputation to offer a more favorable outlook and extended lifespan for feline patients with osteosarcoma.

What is Cat Cancer?

Cat cancer, also known as feline neoplasia, refers to the abnormal growth of cells in a cat’s body. These cells divide and proliferate uncontrollably, forming masses or tumors. These tumors can be benign, meaning they are non-cancerous and unlikely to spread, or malignant, indicating a cancerous growth with the potential to spread to other parts of the body.

Benign tumors are typically slow-growing and do not invade nearby tissues or spread to distant sites. They are usually well-defined and encapsulated, making them easier to remove surgically. 

Malignant tumors, on the other hand, are aggressive and can infiltrate surrounding tissues, invade blood vessels and lymph nodes, and spread to distant organs through metastasis. Treatment for malignant tumors often involves a combination of surgery, chemotherapy, and radiation therapy.

vet explains cat cancer

Common Types of Cat Cancer

There are several types of cat cancer, each affecting different organs or body systems. Some common types include: 

Mammary Gland Cancer

This type of cancer affects the mammary glands in female cats and is more common in older, unspayed cats. Mammary gland tumors can be benign or malignant, with the latter being more aggressive and prone to metastasis. Early detection and surgical removal of the tumor offer the best chance of a positive outcome.

Symptoms of Mammary Gland Cancer in Cats

Lumps or Masses: The most common sign of mammary gland cancer in cats is the presence of a lump or mass in the mammary gland area. These lumps may vary in size and may be single or multiple.

Swollen or Enlarged Mammary Glands: The mammary glands may become swollen, enlarged, or asymmetrical.

Pain or Discomfort: Cats with mammary gland cancer may exhibit signs of pain or discomfort when the affected area is touched.

Ulceration or Open Wounds: In advanced cases, the skin over the tumor may become ulcerated or develop open wounds.

Changes in Nipple Appearance: The nipples may change in color, shape, or size.

Lethargy: Cats with mammary gland cancer may appear lethargic and have a reduced appetite.

Types of Mammary Gland Cancer in Cats

There are different types of mammary gland tumors in cats, which can be classified based on their appearance and biological behavior:

Mammary Adenocarcinoma: This is the most common and aggressive type of mammary gland cancer in cats. Adenocarcinomas tend to spread to nearby lymph nodes and other organs.

Mammary Fibroadenoma: Unlike adenocarcinomas, fibroadenomas are generally benign (non-cancerous) tumors. However, in some cases, they can progress to malignant tumors, so they should still be closely monitored.

Mammary Carcinoma in Situ: This type refers to early-stage malignant tumors that have not invaded surrounding tissues. Early detection and treatment are crucial to preventing the spread of cancer.

Risk Factors:

Gender: Female cats are at a higher risk compared to males, especially if they have not been spayed.

Age: The risk of developing mammary gland tumors increases with age, with the highest incidence in cats between 10 to 14 years old.

Hormonal Influence: Cats that have been spayed before their first heat cycle have a significantly lower risk of developing mammary gland cancer.

breast cancer in cat removal


Lymphoma (lymphosarcoma) is a cancer of the lymphatic system and can occur in various parts of the body, including lymph nodes, intestines, and liver. It is one of the most common types of cancer in cats and can present with a range of symptoms depending on the affected organs. 

Symptoms of Lymphoma in Cats

The symptoms of lymphoma in cats can vary depending on the location and extent of the cancer. Some common signs to watch out for include:

Enlarged Lymph Nodes: One of the most prominent signs of lymphoma is the enlargement of lymph nodes, such as those found under the jaw, in the armpits, or behind the knees. These swollen nodes may feel firm or lumpy.

Loss of Appetite: Cats with lymphoma may experience a decreased appetite and weight loss.

Lethargy: Lymphoma can cause cats to become lethargic and less interested in their usual activities.

Vomiting and Diarrhea: Gastrointestinal lymphoma can lead to vomiting, diarrhea, and changes in bowel habits.

Respiratory Distress: In cases of mediastinal lymphoma (affecting the area between the lungs), cats may show difficulty breathing or coughing.

Pale Gums: Anemia, resulting from cancer’s impact on the bone marrow, may lead to pale gums.

Increased Thirst and Urination: Cats with lymphoma affecting the kidneys may drink and urinate more frequently.

Types of Lymphoma in Cats

Multicentric Lymphoma: This is the most common form of feline lymphoma, where multiple lymph nodes throughout the body are affected.

Gastrointestinal Lymphoma: This type affects the digestive tract, including the stomach and intestines.

Mediastinal Lymphoma: It involves the lymph nodes in the chest area, between the lungs.

Nasal Lymphoma: This type affects the nasal cavity and may cause nasal discharge and breathing difficulties.

Renal Lymphoma: Renal lymphoma targets the kidneys and can lead to kidney failure.

Extranodal Lymphoma: Extranodal lymphoma can affect various organs outside the lymph nodes, such as the liver, spleen, skin, or eyes.

Lymphoma in cats

Squamous Cell Carcinoma 

Squamous Cell Carcinoma (SCC) affects the skin, particularly the ears, nose, and eyelids, and is more common in cats with white or lightly pigmented fur. Squamous cell carcinoma is often associated with sun exposure and can be aggressive, invading nearby tissues. 

Symptoms of Squamous Cell Carcinoma in Cats

The symptoms of SCC in cats can vary depending on the location and extent of the cancer. Some common signs to watch out for include:

Ulcerated or Non-Healing Sores: SCC often presents as non-healing sores or ulcers on the skin. These may be slow to respond to treatment or recur after initial improvement.

Raised or Crusty Lesions: In some cases, SCC can appear as raised, crusty, or scaly lesions on the skin.

Red or Inflamed Areas: Affected areas of the skin may appear red, inflamed, or irritated.

Bleeding: SCC tumors may be prone to bleeding, especially if they are located in areas where the skin is easily traumatized, such as the ears or nose.

Pain or Discomfort: Cats with SCC may exhibit signs of pain or discomfort in the affected areas.

Difficulty Eating or Swallowing: If SCC occurs in the mouth or throat (oral SCC), cats may have difficulty eating, excessive drooling, or weight loss.

Nasal Discharge or Breathing Difficulties: Nasal SCC can cause nasal discharge, sneezing, or difficulty breathing.

Types of Squamous Cell Carcinoma in Cats

SCC in cats can be classified into several types based on its location and behavior:

Cutaneous SCC: This is the most common type and affects the skin, particularly areas exposed to the sun, such as the ears, nose, eyelids, and face.

Oral SCC: Oral SCC occurs in the mouth and can affect the gums, tongue, or roof of the mouth.

oral cancer in cats

Nasal SCC: Nasal SCC affects the nasal passages and can cause breathing difficulties and nasal discharge.

Conjunctival SCC: This type affects the conjunctiva, which is the thin, moist tissue covering the eyeball and lining the eyelids.

Ear Canal SCC: SCC can occur in the ear canal, leading to ear pain, head shaking, and discharge.

Esophageal SCC: Esophageal SCC affects the esophagus, the tube connecting the mouth to the stomach, and can lead to difficulty swallowing.

Bone cancer 

Bone cancer, also known as osteosarcoma, is a rare but aggressive form of cancer that affects the bones of cats. 

Symptoms of Bone Cancer in Cats

The symptoms of bone cancer in cats can vary depending on the location and extent of the tumor. Some common signs to watch out for include:

Lameness: Bone cancer can cause lameness or limping, especially in the affected leg or limb. The cat may avoid putting weight on the affected limb.

Swelling: A noticeable swelling or lump may be present over the affected bone.

Pain or Discomfort: Cats with bone cancer may exhibit signs of pain, such as vocalizing, reluctance to move, or aggression when the affected area is touched.

Fractures: Bone cancer can weaken the bone, making it more susceptible to fractures or breaks.

Decreased Appetite and Activity: Cats with bone cancer may experience a decreased appetite and reduced activity due to pain and discomfort.

Lethargy: Bone cancer can lead to lethargy or a lack of interest in normal activities.

Types of Bone Cancer in Cats

Osteosarcoma: Osteosarcoma is cats’ most common and aggressive form of bone cancer. It typically affects the long bones, such as the legs, and can spread to other areas of the body.

Chondrosarcoma: Chondrosarcoma is a type of bone cancer that originates from cartilage cells. It is less common than osteosarcoma and tends to occur in the ribs or nasal cavity.

Fibrosarcoma: Fibrosarcoma is a cancer of the fibrous connective tissue and can occur in the bones of cats.

Causes of Cat Cancer

The causes of cat cancer can be multifactorial, often involving a combination of genetic and environmental factors. 

Age: Like in humans, age is a significant risk factor for cancer in cats. As cats age, the likelihood of developing cancer increases, especially in older cats over the age of 10 years.

Genetics: Genetic factors can play a role in certain types of cancer. Some cat breeds may have a higher predisposition to specific types of cancer due to genetic mutations.

Breed Predisposition: Certain cat breeds may have a higher likelihood of developing certain types of cancer. For example, Siamese cats may be more prone to gastrointestinal cancers, while Scottish Folds may have an increased risk of developing certain bone and cartilage cancers.

Exposure to Carcinogens: Cats exposed to certain environmental carcinogens may have an increased risk of developing cancer. These may include tobacco smoke, certain chemicals, pesticides, and some environmental pollutants.

Chronic Inflammation: Chronic inflammation or long-term irritation of tissues can sometimes increase the risk of cancer development. Inflammation can be caused by infections, dental issues, or chronic irritants.

Obesity: Overweight and obese cats may have a higher risk of developing certain types of cancer, such as mammary gland cancer.

Exposure to Sunlight: Cats with light-colored or thin fur, especially on their ears and noses, may be at a higher risk of developing squamous cell carcinoma (skin cancer) due to exposure to sunlight.

Hormonal Factors: In unspayed female cats, the risk of developing mammary gland cancer may increase with the number of heat cycles they experience.

Viral Infections: Certain viral infections, such as feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV), can increase the risk of certain types of cancer, including lymphoma.

Cancer can be a complex disease, and many cases may involve a combination of factors. Nnot all cats exposed to risk factors will develop cancer, and not all cases of cancer have an identifiable cause. 

Regular veterinary check-ups, early detection, and a healthy lifestyle can help reduce the risk of cancer and improve the overall well-being of your feline companion. If you have concerns about your cat’s health or potential risk factors, consult your veterinarian for personalized advice and preventive measures.

What are signs of cancer in cats?

When it comes to cat cancer, there are both physical and behavioral changes that you should be on the lookout for. These changes can indicate the presence of a tumor or other underlying health issues.

Physical Changes

One of the most common signs of cat cancer is unexplained weight loss. If your cat is losing weight despite having a normal or increased appetite, it could be a cause for concern. 

Lumps or swelling in different parts of the body, such as the neck, abdomen, or limbs, should not be ignored. These abnormal growths may require further investigation to determine if they are cancerous.

Presence of sores that do not heal. Cats are generally good at grooming themselves, and any persistent sores or wounds that fail to heal may be an indication of a more serious underlying condition. 

Persistent Coughing or Difficulty Breathing: Respiratory symptoms, such as coughing or difficulty breathing, can be signs of lung cancer or tumors in the chest.

Behavioral Changes

Pay attention to any unusual lethargy or decreased activity levels. If your cat is suddenly less active or seems to lack energy, it may be a sign that something is wrong. Increased aggression or irritability can also be a symptom of cat cancer. 

If your cat’s behavior has become noticeably more aggressive or if they are displaying uncharacteristic hostility, it is worth investigating further.

Changes in litter box habits can be indicative of health issues, including cancer. If your cat starts urinating or defecating outside of the litter box, it may be a sign of discomfort or pain. 

Changes in Urination or Defecation: Changes in urinary or bowel habits, such as difficulty urinating, blood in the urine, diarrhea, and constipation may indicate cancer affecting the urinary or digestive system.

Sudden changes in vocalization patterns, such as excessive meowing or a significant decrease in vocalizations, should also be noted. These behavioral changes can provide valuable clues about your cat’s overall health and should not be ignored.

When to Consult a Vet

If you observe any of the symptoms or if you have concerns about your cat’s health, it is crucial to consult a veterinarian. Only a qualified medical professional can adequately diagnose cat cancer through a thorough examination and diagnostic tests. 

Your vet may perform blood tests, X-rays, ultrasounds, or biopsies to determine if cancer is present and to identify the specific type and stage of the disease.

Treatment Options for Cat Cancer

While cat cancer can be devastating, there are treatment options available that can help alleviate symptoms, slow the progression of the disease, and improve your cat’s quality of life.


Surgery is often the primary treatment option for localized tumors. Surgical removal of the tumor, along with a margin of healthy tissue, aims to eliminate the cancerous cells and prevent further spread. Depending on the location and size of the tumor, your veterinarian will determine the feasibility of surgical intervention.

Chemotherapy and Radiation

Chemotherapy and radiation therapy are commonly used in cats with cancer that has spread or cannot be surgically removed. These treatments aim to kill cancer cells or slow down their growth. Your veterinarian will develop a personalized treatment plan based on your cat’s specific type and stage of cancer.

Palliative Care

In cases where the cancer is advanced and cannot be cured, palliative care focuses on managing pain and discomfort and improving your cat’s quality of life. This may involve pain medication, dietary changes, or other supportive treatments tailored to your cat’s individual needs.

Cat Cancer Home Care

Cats diagnosed with cancer require special care to maintain their physical health and ensure comfort during their remaining days. 

Veterinary oncologists can offer a second opinion and aid in pain management

Owners should monitor breathing abnormalities and administer pain medications as needed. 

Home care, nutrition, and hydration are crucial, especially if cancer affects the gastrointestinal tract or oral region. 

If a cat becomes inactive and unable to groom, owners should assist with grooming and adapt the environment to cater to their comfort. 

Create a safe and comfortable environment for your cat to minimize stress and promote relaxation. Offer cozy resting spots, regular playtime, and affectionate interaction to keep your cat mentally stimulated and emotionally supported.

If your cat is unable to walk you can opt for cat strollers

Vet Q$A

Q: Do cats with cancer smell bad?

A: Yes, a freshly foul smell coming from your pet might be a sign of skin tumors, including melanoma (cancer of skin pigment cells), squamous cell carcinoma (cancer of skin cells), and fibrosarcoma (cancer of connective tissues). 

Q: Is cancer painful for cats?

A: Yes, cancer in cats can be painful. If the tumor enlarges and puts pressure on surrounding areas or if the tumor becomes ulcerated, especially with squamous cell carcinomas.

Q: How did I not know my cat had cancer?

A: Cats are masters in hiding symptoms and pain. Not all cancers are painful, some start showing at later stages. Regular vet visits are the best prevention. 

Q: Cat cancer life expectancy

A: Survival time for cats with lymphoma can be prolonged with chemotherapy, extending it from an average of two months to up to 12 months or even longer in some cases.

Some types of feline cancer, like mammary cancer and certain skin cancers, can be managed and even reversed if detected early. pessimistic prognosis