According to Animal Cancer Foundation, 1 in 5 cats will develop cancer in their lifetime. Cancer in cats is actually less common than cancer in dogs, but once it is diagnosed, it tends to move faster. Knowledge is power, and our role as pet parents is to be armed with information and provide our companions with the best possible care. Yet, how much do we really know about this deadly disease in cats? It's time to talk science!

Please note that due to the complexity of the issue, we decided to split this article into two parts. The first part covered the background information and explained what cancer is, how it develops and what causes it. The second part will focus on the types of feline cancer, treatment, and prevention. Here, we will address the following:

1) Most common types of feline cancer.

2) Diagnosis of feline cancer.

3) Treatment of feline cancer.

4) Prevention of feline cancer.

Most common types of feline cancer

The most common cancer types found in cats are lymphomas, skin cancers, cancer of the mammary glands and abdominal cancers.

a) The most common form of cancer in cats is lymphoma, which is often associated with feline leukemia virus (FeLV). It is estimated that feline lymphoma accounts for roughly 90% of all cases of blood cancer cases and 33% of all cases in total. Lymphoma is cancer of the lymphocytes, a type of white blood cells that play a very important role in the immune system. Some of the most common forms of this cancer are:

1. Mediastinal form – occurs between pleural sacs/lungs.

2. Alimentary form – occurs in the gastrointestinal tract, abdomen, and liver.

3. Multicentric form – occurs in the lymph nodes.

4. Solitary form – this one can occur in any location.

5. Renal form – occurs in the kidneys.

Symptoms can highly vary depending on the form of the lymphoma, but the most common symptoms are: lumps that vary in shape and size, sores that do not heal, changes in bowel or bladder habits, urinating difficulties, eating difficulties, strange bleeding, changes in appetite and body weight, coughing, breathing difficulties, and oral odor.

b) Less common among cats are feline skin tumors. White cats are generally more prone to this type of cancer. Skin tumors usually form visible lumps on the skin and affect vision, smell, eating habits or physical activity. Benign skin tumors are more difficult to detect due to their mobility and long period of development. Note that not all bumps and lumps are in fact cancer! There are a lot of other types of bumps that can be found on or under the surface of the skin which do not necessarily represent abnormal tissue growth. If you notice anything odd on your cat’s skin, see your veterinarian as soon as possible to ensure a timely diagnosis.

c) The Third most common feline cancer is cancer of the mammary glands which usually manifests as a lump in the breast tissue. This is the most frequent type of cancer in cats older than 10 years of age.

It is not known what exactly causes this form of feline cancer, as the underlying genetic factor hasn’t been found yet. However, the hormonal status and breed seem to play a role in the development of this cancer. Dr. McEntee says: “If these hormones [estrogen and progesterone] are given to unspayed cats as contraceptives or for behavior modification either orally or by injection, their risk of mammary cancer can triple.” She also notes: “Siamese cats, for unknown reasons, have twice the risk of other breeds, and they also tend to get the cancer at an earlier age.” It is estimated that spaying the cat before the age of six months reduces the risk of mammary cancer by 91%. Spaying cats also decreases the chances of ovarian cancer by 40-60%.

d) Some of the rarest and most difficult feline cancers to treat are abdominal cancers. Cats suffering from these types of cancers will often experience poor digestion, weight loss, overall weakness, vomiting and abdominal enlargement.

Diagnosis of feline cancer

Detecting abnormalities at an early stage is crucial for the successful treatment of this complex disease. Common diagnosing methods are a physical examination, x-rays, ultrasounds, blood and urine tests, and cytology tests. Some cancers are easier to detect than others. For example, skin and mammary tumors often manifest with physical symptoms which cat owners can often notice themselves.! In such cases, owners are urged to see a veterinarian promptly! Unfortunately, not all cancers can be diagnosed by a visual observation and other diagnosing methods must be utilized.

Treatment of feline cancer

The strategy behind the treatment of feline cancer is determined only once the diagnosis has been established and the type and size of the tumor have been described. If the location of the tumor is safely accessible, then surgical removal can be an effective form of treatment. This is by far the most common treatment of choice. Depending on the diagnosis, radiation therapy, chemotherapy, and immunotherapy are often utilized as well.

Today, new research studies are continuously conducted in efforts to find more precise and personalized ways to address cancer in humans and our companion animals. New anticancer agents are being developed, as well as new ways of their application. For example, in human medicine lately, liposomes and nanoparticles have been examined as novel drug delivery systems for anticancer agents. Liposomes and nanoparticles have the ability to target individual cancerous cells and therefore can administer a more precise application of treatment drugs. This form of delivery would greatly decrease the negative side effects free cytostatic drugs have on healthy neighboring cells.

Prevention of feline cancer

Just like in humans, major factors that can influence the risk of developing cancer in cats are lifestyle and genetics. While genetic factors and exposure to some environmental factors may not be avoidable or preventable, it is within your control to provide your cat with a complete, healthy and balanced diet, as well as making sure they enjoy an active lifestyle.. Minimize indoor pollution by preventing your cat from being exposed to cigarette smoke and direct sunlight for prolonged periods of time.

If your kitty is white, it is not recommended to let her out on sunny days between 10 am and 4 pm, when the sun is at its highest peak. If this is not an option for you, then you may want to consider sunblock available for cats. Remember, that a major factor in cancer treatment is early diagnosis. As a general rule of thumb, the best thing you can do as a pet parent is take your feline friend in to see the vet for regular check-ups, which will drastically increase the chances of finding odd signs and symptoms at an early stage.

Interestingly enough, there may be a link between spaying and neutering, and cancer development. Spaying female cats can decrease the risk of mammary gland cancer, ovarian cancer, and uterine cancer development, as it prevents them from going into heat. This is because the primary cause of these cancers is reproductive hormones and spaying prevents female cats from releasing these hormones. Same way, neutering males can help reduce the risk of developing testicular cancer, as it would make them less subjected to FeLV and FIV.

There are many different types of cancer in cats and many diverse approaches when it comes to each types’ diagnosis, treatment and prevention. Hopefully, this article together with part 1, provided a better understanding of feline cancer and its global effect on feline health.

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