According to the Animal Cancer Foundation, 1 in every 5 cats will develop cancer in their lifetime. Cancer in cats can occur at any age, but it’s most commonly seen in middle-aged to older kitties, where it’s the leading cause of death.
Although cancer in cats is less common than cancer in dogs (it occurs at roughly half the rate), when it does occur, it tends to be more aggressive. It can also be much harder to detect because cats are so good at hiding pain and illness. Personally, I’ve lost 3 cats to cancer over the years, and in each case I had no idea that any of my babies were sick until it was too late to do anything about it. As a former veterinary professional, this was utterly devastating, and I struggled with tremendous feelings of guilt over not having seen the signs earlier. It’s amazing how sick a cat can truly be before he or she starts exhibiting any symptoms.
So What Is Cancer, Exactly?
Simply put, cancer is a disease where the DNA (genetic code) of a normal cell becomes damaged, causing the cell to mutate. This damage can be caused by a virus, radiation, exposure to chemicals (such as pesticides or herbicides), or some types of hormones. The negative effects of these agents can build up over the years, which could explain why so many cancers affect older animals.
The damaged cell begins to go rogue and starts replicating itself, unchecked. The resulting cells then invade surrounding tissue, where they cause new blood vessels to grow around them to supply them with nutrients. This is what allows the cancer to spread (or metastasize) to other areas of the body.
Although many things can contribute to cell damage, in most cases the exact cause of a pet’s cancer is never identified. Both the environment and heredity may contribute to the development of cancer in cats, but most times we never know what really causes it.
Signs Of Cancer In Cats
Although cats are very skilled at hiding signs of illness, when it comes to cancer, there are general symptoms to watch out for. These can include:
- Lumps, bumps, or any abnormal growth or swelling that doesn’t go away
- Rapid weight loss
- A rough hair coat, or mats in the coat from lack of grooming
- Unusual foul odor, especially from the mouth
- An open or scabby sore that won’t heal
- Dramatic change in appetite, or refusal to eat
- Difficulty swallowing or eating
- Pale gum color
- Bleeding from the mouth
- Swelling or bloating in the abdomen
- Weakness and fatigue
- Coughing, wheezing, or difficulty breathing
- Persistent vomiting or diarrhea
Also watch for any behavioral changes that are out of the ordinary. A cat who begins sleeping in rooms he typically doesn’t go into, avoiding people or other pets, or hiding in unusual places may be sick or in pain.
The Most Common Types Of Cancer In Cats
The 3 most common types of cancer in cats are lymphoma (also called lymphosarcoma), squamous cell carcinoma, and fibrosarcoma.
Lymphoma is a cancer of the lymphatic system, and it’s the most common cancer seen in cats. It typically affects the lymph nodes, intestines, liver, spleen, kidneys, chest cavity, and/or nasal cavity. Although lymphoma in dogs causes swollen lymph nodes which can be easily felt as lumps under the skin, lymphoma in cats is much more stealthy. The most common symptoms when the intestinal form is present are persistent vomiting, diarrhea, and weight loss.
Feline lymphoma has been strongly linked to infection with the Feline Leukemia and Feline Immunodeficiency viruses (FeLV and FIV). Cats with FeLV are 60 times more likely to develop lymphoma. Also, cats who live in smoking households are twice as likely to acquire lymphoma than cats who live with nonsmokers.
Fortunately, lymphoma is one of the more treatable forms of cancer in cats. It typically responds very well to chemotherapy, with up to 75% of treated cats going into remission, some for as long as 2 years or more. Cats who have been treated for lymphoma also seem to enjoy a high quality of life while they are in remission.
Squamous Cell Carcinoma
There are 2 forms of squamous cell carcinoma (SCC): a skin form and an oral form. The skin form typically develops as scabby ulcers on the ear tips, nose, and eyelids. Like human skin cancer, it’s caused by exposure to the sun, and is more common in older, white or lighter-colored cats. The oral form develops in the mouth, and can invade the surrounding jaw bone, causing swelling, bleeding from the mouth, and severe weight loss from the cat being unable to eat.
For the skin form of SCC, the prognosis can be good if it’s caught and treated early. Unfortunately, the oral form of SCC is much worse than the skin form. It’s very aggressive and difficult to treat, and since 95% of oral SCC cases are only found once there are dramatic changes in the cat’s appearance (such as blood in the mouth or swelling of the face and jaw), by the time it’s found, the cancer is often too far advanced to treat.
Like lymphoma, the oral form of SCC has also been linked to exposure to second-hand smoke. It’s believed that the toxins from airborne cigarette smoke settle on cats’ fur and are ingested when they groom themselves, leading to cancer of the mouth.
Fibrosarcoma is an aggressive tumor that develops in the body’s fibrous connective tissue. The most common site for fibrosarcomas in cats are on the upper back, between the shoulder blades. Because this is also the site where cats are typically vaccinated, several years ago researchers began investigating whether there could be a link between the administration of vaccines and the development of fibrosarcoma – and they found one.
Although it was found that fibrosarcoma formation has been associated with injections of vaccines, steroids, antibiotics, and insulin, the most common link was to vaccines, particularly the Rabies and Feline Leukemia (FeLV) vaccine. However, according to the American Veterinary Medical Association, this occurrence is still relatively rare, estimated at 1 case per 10,000 vaccinations.
This brings up an interesting dilemma, because the advent of the FeLV vaccine has reduced the overall incidence of Feline Leukemia, a virus which has been directly linked to the development of lymphoma. So cat parents must weigh the risk of giving the FeLV vaccine against the risk of possible exposure of their cats to the FeLV virus.
To reduce this risk, many veterinarians have now begun limiting how often they give vaccinations, and have started using different rotating injection sites to help reduce potential inflammation in the same area (since chronic inflammation has been linked to the development of cancer).
Treatment for fibrosarcoma is aggressive surgery (where not only the tumor is removed, but also a wide section of surrounding tissue), followed by chemotherapy. Unfortunately, even with treatment, these tumors have a tendency to return, sometimes fairly quickly.
Other Types of Cancer In Cats
Cats are susceptible to other types of cancer as well, including:
- Mast cell tumors, which affect the skin and internal organs
- Mammary gland tumors (breast cancer), usually seen in female cats who are not spayed
- Intestinal adenocarcinoma, a cancer of the intestinal tract
- Lung cancer
- Liver tumors
- Tumors in the nasal cavity
- Brain tumors
Diagnosing cancer in cats can be tricky. If you or your veterinarian find an obvious lump anywhere on your cat’s body, the first step is to take a sample of cells from the mass. This is done by either sticking a needle into the lump and drawing up some cells, or with a surgical biopsy (where a sample is taken under general anesthesia). The cells are then sent to a lab, where a pathologist can examine and identify them.
If your cat is just not acting right, or seems ill and you don’t know why, radiographs (x-rays) or ultrasound can be used to see if there are any suspicious-looking growths in the lungs, liver, spleen, or abdomen. Your veterinarian can also run blood tests, which will show any abnormalities that could indicate cancer somewhere in the body.
Whole-body CT scans, which are relatively new in veterinary medicine and are proving to be invaluable in diagnosing cancer, can also be used to view and identify abnormalities in everything from internal organs to the brain.
Treatment Options For Cats With Cancer
Regardless of the type of cancer present, the goals of treatment are always the same: to remove all cancerous tissue whenever possible, and to prevent any cancer cells that are there from spreading.
For many cancers (especially if they’re caught early), there are different types of treatments available to either wipe out the cancer completely, or keep it at bay for a long enough period of time to extend a cat’s length and quality of life for as long as possible. Which method is used will depend on the type of cancer present. These include:
- Surgery – surgical removal of the tumor and any surrounding tissue that may have been invaded.
- Chemotherapy – the use of chemotherapeutic drugs (given either orally or through an IV) designed to poison and destroy all rapidly-dividing cells in the body.
- Radiation therapy – the use of highly-targeted radiation to kill malignant cancer cells. Radiation therapy is particularly helpful for targeting cells deep in the brain and nasal cavity, areas that were previously inaccessible to surgeons.
What’s The Prognosis For A Cat With Cancer?
The prognosis for a cat with cancer can be extremely difficult to state with any degree of certainty. Many factors need to be taken into consideration: the type of cancer, location of the tumor, age of the cat, whether the cancer was caught early or in later stages, or if the cancer has already spread.
The good news is that modern cancer management doesn’t just involve killing cancer cells. Successful management of cancer includes pain control, good nutritional support, even alternative therapies such as acupuncture and diet therapy.
How To Give Your Cat A Fighting Chance Against Cancer
Since the exact cause of cancer is often difficult to determine, it makes it hard to know with any degree of certainty if we’re ever truly able to prevent it from happening to our cats. However, there are definitely things that can be done to greatly reduce the risk of your cat developing cancer:
- Early detection. When it comes to cancer, this is probably the most important thing you can do to protect your kitty. Since the early signs of cancer can easily be missed, it’s important to have regular vet visits and annual examinations, especially as your cat gets older. If you notice anything unusual, report it to your veterinarian.
Of the 3 cats I lost to cancer over the years, 2 of them (Emily and Jasper) had brain tumors. Looking back, I remembered that even though those cases were almost 20 years apart, both of them had experienced very short episodes where they were ever-so-slightly squinting in one eye. Since the squinting was barely perceptible and lasted such a short time, I had assumed in both cases they had just gotten bumped in the eye while playing, or the eye had gotten irritated. Looking back, I believe that this was the earliest outward sign of their brain cancer, and I had missed it both times – a mistake I hope to never make again. When in doubt, check it out.
- Make sure your female cat is spayed, which will greatly reduce her risk of developing breast cancer.
- If you smoke around your cat, please stop. Cats are extremely susceptible to the effects of second-hand smoke, which can result in cancerous tumor formation and the development of asthma.
- Keep your cat indoors. This prevents exposure to other cats who may be infected with the FeLV and FIV viruses, as well as exposure to the sun’s ultraviolet rays (especially if your cat has white fur), both of which have been linked to cancer in cats.
- Keep your cat at a healthy weight and feed a nutritionally-balanced diet.
The good news is that recent advances have enabled veterinarians to begin treating cancers in cats and dogs that have previously been considered untreatable. Chemotherapy and radiation treatment in pets is also less aggressive than in humans, so the side effects are usually less severe.
However, as with all pets, quality of life is the most important thing to consider when deciding whether to pursue treatment for a cat with cancer. If your cat is diagnosed with cancer, talk with your veterinarian about referring you to a veterinary oncologist, a cancer specialist who has access to the most up-to-date treatments. He or she can discuss all aspects of your cat’s diagnosis with you, including treatment options, prognosis, access to clinical trials, even the development of a customized care plan for making your cat as comfortable as possible at home if treatment isn’t an option.
To learn more about cancer in cats, be sure to talk with your veterinarian and visit the Veterinary Cancer Society website, a valuable resource for pet parents dealing with a cancer diagnosis.
Have you ever had a cat who was diagnosed with cancer? Please share your story with us in the comments below!