Cancer in cats is a significant veterinary health challenge, with certain tumor types and treatment approaches increasingly studied in recent years. Feline cancer presents unique features and treatment considerations compared to other species. This article synthesizes findings from peer-reviewed scientific literature published primarily within the last five years, focusing on common cancers in cats, clinical signs, diagnostic strategies, and recent advances in therapy.Approximately 20% of cats (1 in 5) will be diagnosed with cancer during their lifetime.For cats over 10 years old, cancer accounts for about 32% of deaths according to Colorado State University.
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What are the Most Common Types of Cancer in Cats?
Lymphoma is the most frequently diagnosed cancer in cats, affecting lymphoid tissues such as the lymph nodes, gastrointestinal tract, and kidneys. Cats with lymphoma may exhibit symptoms like weight loss, vomiting, diarrhea, and decreased appetite, with small cell gastrointestinal lymphoma being common and often responding well to treatment.
Squamous cell carcinoma (SCC) is the most common oral tumor in cats, typically presenting as non-healing mouth ulcers, facial swelling, bad breath, drooling, and difficulty eating. SCC is locally aggressive and can invade bone, often necessitating surgery or radiation, and its skin forms—especially on the ears or nose—are linked to sun exposure. Fibrosarcoma, a cancer of the soft tissues like muscle or connective tissue, is locally invasive but slow to metastasize; rare injection-site sarcomas can occur at vaccination sites.
Mammary tumors, usually malignant adenocarcinomas, occur primarily in intact or older female cats and often spread to lymph nodes and lungs, though early spaying greatly reduces risk. Mast cell tumors (mastocytomas) arise from immune cells and can affect the skin or spleen, ranging from benign to malignant in behavior. Osteosarcoma is a bone cancer that causes pain and swelling, tends to be aggressive, and carries a high risk of metastasis.
What are the Common Symptoms of Cancer in Cats?
Cancer in cats can present with a variety of symptoms that often overlap with other health conditions. One of the most noticeable signs are abnormal lumps or masses under the skin or in the mouth, non-healing sores or ulcers, weight loss and reduced appetite, lethargy and behavioral changes, drooling, bad breath, or difficulty eating (oral cancers), enlarged lymph nodes,changes in urination or defecation, bleeding or discharge from unusual sites, unexplained lameness or limping (particularly with bone tumors).
What Diagnosis Do They Involve?
Physical exam and medical history. Advanced imaging( X-rays, ultrasound, CT, MRI) for tumor localization and staging.Laboratory tests (bloodwork and urinalysis) for systemic health. Fine needle aspirates and biopsies for definitive diagnosis and tumor grading,staging using TNM system to assess tumor size, lymph node involvement, and metastasis.
Regular Veterinary Check-Ups
- Frequency: Adult cats (7+ years) should have check-ups at least every 6–12 months; senior cats (10+ years) may benefit from even more frequent visits.
- Physical Examination: At each visit, the veterinarian should thoroughly palpate for lumps, check lymph nodes, inspect the mouth, and assess for any subtle signs of illness.
- Baseline and Monitoring Tests: Bloodwork and urinalysis help assess organ health and may reveal paraneoplastic syndromes or other unrelated conditions.Routine FeLV/FIV testing is warranted for cats at risk or presenting with chronic illness.
- Prompt Evaluation of New Symptoms: Owners should seek veterinary attention if they notice new lumps, persistent sores, weight loss, or any abrupt behavioral changes.
What Treatments Do We Have For Cancer In Cats?
- Surgery is primary for localized, resectable tumors, aiming for clean surgical margins.
- Chemotherapy protocols are tailored for feline tolerance, with agents like lomustine, methotrexate, and cytarabine showing efficacy and reasonable tolerability, especially when used as rescue treatments for lymphoma.
- Radiation Therapy complements surgery for incompletely resected or inoperable tumors.
- Emerging Immunotherapies, such as oncolytic virus-based treatments (e.g., Newcastle Disease Virus strains targeting lymphoma cells), are promising new frontiers under active investigation.
- Palliative Care focuses on optimizing quality of life when curative treatments are not feasible.
Treatment choices depend on tumor type, stage, location, the dog’s health, and owner goals.
Preventive Strategies
Early spaying, ideally before six months of age, is highly effective in reducing the risk of mammary gland tumors, which are often malignant in cats. To lower the risk of injection-site sarcomas (feline injection-site sarcoma, FISS), cats should only be vaccinated as frequently as necessary according to current veterinary guidelines. Vaccines and other injections are best administered as distally as possible on the limbs or in the tail rather than in the interscapular region or lateral thoracic wall, making potential surgical removal easier if tumors develop.
Where available, non-injectable vaccines such as intranasal forms are preferred to further reduce risk. It is also important to minimize your cat’s exposure to known environmental carcinogens, including tobacco smoke and excessive ultraviolet light—especially for light-colored cats at risk for squamous cell carcinoma in sun-exposed areas like the ears and nose. For monitoring after injections, follow the “3-2-1” rule: any lump that lasts more than three months, measures over two centimeters, or grows in size one month after injection should be promptly evaluated by a veterinarian, as a biopsy may be necessary.
You Can Also Read Cancer in Dogs: Common Types, Symptoms, Diagnosis, and Treatment by Oncodaily
Routine Screening and Veterinary Check-Ups
Adult cats, particularly those over 7 years old, should have veterinary evaluations at least every 6–12 months, while senior cats (10+ years) may benefit from visits every 6 months or more frequently. These exams should include a thorough physical examination, including palpation for lumps, lymph node assessments, oral inspections, and skin checks.
Diagnostic imaging, such as X-rays or ultrasounds, may be recommended annually or as needed to screen for internal tumors, especially if risk factors or symptoms are present. Routine bloodwork and urine tests can help detect systemic effects of cancer or other illnesses early. In addition to veterinary visits, cat owners are encouraged to regularly check their pets for new lumps, non-healing wounds, weight loss, or behavioral changes and promptly report any concerns to their veterinarian.
Written by Tatev Ghazaryan
FAQ
How common is cancer in cats?
Roughly 6 million cats in the United States are diagnosed with cancer each year, and about 20% of cats will be affected during their lifetime.
What causes cancer in cats?
Causes can include genetics, environmental exposure (like UV light or tobacco smoke), infection with viruses such as feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV), chronic inflammation (like injection-site sarcomas), and age.
How is cancer diagnosed in cats?
Diagnosis may involve a physical exam, blood tests, x-rays, ultrasounds, CT or MRI scans, fine needle aspiration, and biopsies sent to labs for analysis.
Can cancer in cats be treated?
Yes, depending on the type and stage, treatment can include surgery, chemotherapy, radiation therapy, immunotherapy, or palliative care for quality of life.
What is the prognosis for cats with cancer?
Prognosis varies with cancer type, stage, and your cat’s overall health. Some cancers are treatable and can be managed for months or years; others may carry a shorter prognosis.
Does cancer cause pain in cats?
Yes, cancer can cause pain due to tumor growth, pressure on organs or nerves, or ulceration. Pain management is an important part of cancer care.
Are cats with cancer contagious to other pets or humans?
Cancer itself is not contagious, but some viruses that increase cancer risk (such as FeLV or FIV) can be transmitted between cats.
What is cancer in cats?
Cancer is an abnormal and uncontrolled growth of cells, which can form tumors or spread throughout the body.
