Cat Cancer: Types, Symptoms, Treatments, and Early Detection Tips Explained by a Vet

Due to improvements in living environments and advancements in veterinary medicine, the average lifespan of cats has increased to approximately 15 years. This is equivalent to about 76 years in human age. Consequently, cancer in senior cats is on the rise and has become one of the top three causes of death.

In this article, we will provide a detailed explanation of cancer in cats.

What is cancer in cats? Incidence and common types

The difference between benign and malignant tumors

The word "tumor" often carries a negative connotation, but by definition, a tumor is a state in which "cells that normally exist within one's own body proliferate autonomously, purposelessly, and excessively." In other words, it occurs when normal cells multiply for some reason. Tumors are categorized as either benign or malignant, with malignant tumors generally being referred to as "cancer."

The definitive difference between benign and malignant tumors is the presence or absence of metastasis. While benign tumors also grow as cells multiply, they have clear boundaries from surrounding tissue, grow slowly, and do not metastasize. On the other hand, malignant tumors grow by destroying surrounding tissues, progress rapidly, and cause metastasis. Another major difference is that they have a very high likelihood of recurring even after treatment.

Incidence of cancer in cats

While cancer is rare in young cats, its incidence tends to increase after age five. In senior cats aged 10, the incidence rate is approximately 5%.

Factors contributing to cancer in cats are diverse, but are thought to include the accumulation of genetic errors due to aging, weakened immunity, persistent inflammation caused by obesity, viral infections (such as feline leukemia virus), hormonal influences, and exposure to chemical substances.

While cancer is often associated with advanced age, cats infected with the feline leukemia virus can develop cancer at a younger age.

Common types of cancer in cats

Common cancers in cats include lymphoma, mammary gland tumors, mast cell tumors, squamous cell carcinoma, and fibrosarcoma. Lymphoma, in particular, accounts for 20% of all tumors.

Main symptoms of feline cancer and warning signs for owners

Loss of appetite, weight loss, vomiting, and diarrhea

Cancers proliferate by depriving surrounding tissues of blood and nutrients. Consequently, an initial symptom can be "losing weight despite having an appetite." Furthermore, many feline cancers occur in the intestinal tract, which can lead to a loss of appetite, as well as increased vomiting and diarrhea. Pain often makes it difficult for cats to eat as well.

How to check for lumps and swelling

Cancers that tend to occur on the skin may be discovered as lumps. Mast cell tumors, squamous cell carcinomas, and fibrosarcomas are often found as skin lumps. Additionally, some forms of lymphoma involve swelling of the body's lymph nodes, which may be discovered as a lump on the jaw.

Regularly touch your cat's body to check for any lumps or bumps. If there is a spot they are constantly licking, it is a good idea to examine that area.

Oral abnormalities such as bad breath, drooling, and bleeding

Squamous cell carcinoma and other cancers that develop in the mouth will show oral abnormalities. Symptoms include severe bad breath, drooling, bleeding from the gums, and an inability to close the mouth.

Respiratory distress and lethargy

As cancer progresses, it can metastasize throughout the body. Pleural or abdominal effusion (fluid buildup) may occur, causing difficulty breathing. Additionally, anemia caused by bleeding, destruction of red blood cells, or decreased production can lead to respiratory distress and a general lack of activity.

Diagnosis and treatment of feline cancer

Diagnosis via blood tests, X-rays, and ultrasounds

Among feline cancers, blood cancers such as lymphoma and leukemia are often detected via blood tests. X-ray and ultrasound examinations are also crucial for cancer diagnosis; they are useful not only for identifying the location of the cancer but also for assessing the presence of abdominal or pleural fluid.

The necessity of CT and MRI scans

The accuracy of X-ray and ultrasound examinations depends on the experience and skill of the attending veterinarian. Furthermore, since X-rays and ultrasounds are difficult to use for the head and spinal cord, precise tests like CT or MRI scans may be necessary.

Options: Surgery, radiation therapy, and chemotherapy

The first-line treatment varies depending on the type of cancer. For blood cancers like lymphoma and leukemia, chemotherapy is the first choice, while surgical excision is the first choice for mast cell tumors and fibrosarcomas. Radiation therapy may be used for certain cancers, such as nasal adenocarcinoma. Many cancers are treated using a combination of these approaches.

Palliative and symptomatic treatment

Cancer treatment includes not only curative therapy aimed at the cancer itself but also palliative care intended to improve quality of life (QOL). Palliative care is often administered when the cancer has spread throughout the body or metastasis has occurred. This may involve using surgery, chemotherapy, or radiation to shrink the tumor as much as possible, combined with symptomatic treatment to alleviate painful conditions such as vomiting or pain.

Tips for preventing and detecting feline cancer early

The importance of regular health checkups

Cancer progresses quickly, and it is not uncommon for metastasis to have already occurred by the time it is discovered. Therefore, regular health checkups are vital. Feline cancer tends to increase from around age five. We recommend examinations at least once a year, preferably twice a year. While the items included in a checkup vary by clinic, we recommend undergoing X-rays and ultrasounds if possible.

The importance of diet and weight control

Cats can obtain all the energy and nutrients necessary to maintain their bodies through cat food and drinking water. Human food often contains high salt levels and additives, which can lead to health issues for cats. This can contribute to various illnesses, not just cancer.
Indoor cats today are often well-nourished, and most tend to be overweight. It is known that obesity can cause persistent inflammation in the body, which has been linked to cancer. Review the quality and quantity of your cat's food to ensure they maintain a healthy weight.

Vaccinations

Some cancers, such as lymphoma, are known to be caused by the feline leukemia virus. Cancers involving viruses tend to develop at a younger age. Feline leukemia is particularly common in cats that go outdoors. Because there is a vaccine for the feline leukemia virus, please ensure your cat is vaccinated if they have the opportunity to go outside.

The World Small Animal Veterinary Association (WSAVA) vaccination guidelines recommend an interval of three years or more for adult cats. The reasons for this include the fact that the vaccine's effectiveness lasts for over three years, and the risk of vaccine-associated fibrosarcoma at the injection site.

Vaccine-associated fibrosarcoma is a cancer that forms a deep-rooted lump at the injection site but is less likely to metastasize. For this reason, it is recommended to inject the vaccine into the hind leg so that the site can be surgically removed (amputated) if necessary. Regularly check the injection site to ensure no lump has formed.

Daily health check tips for owners

Cancers are often advanced by the time they are noticed, and feline cancers are frequently incurable. Early detection and early treatment are essential. Get into the habit of touching your cat to check for lumps, weight loss, or signs of pain. Also, consistently monitor their appetite and energy levels.

Summary

Cancer tends to occur more frequently in senior cats. The key to treatment is early detection and early intervention. To ensure early detection, be sure to schedule regular health checkups and visit a veterinary clinic even for minor abnormalities.