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Zoom Recap: Cancer in Cats—Call #15

Cancer in Cats

Because cancer is so common in cats and it affects all age groups, Indiana small animal veterinarian Dr. Leslie Brooks wanted to use this Zoom call to talk about this vicious disease, including common types along with symptoms and treatment.

Fostering and behavioral specialist Liz Italia co-hosted the call and had her own experience after treating one of her cats with a fibrosarcoma (vaccine-induced cancer).

Recorded: September 28th, 2020.

Disclaimer: The opinions expressed in this call are those of the guest(s) and/or host(s) and may or may not reflect the views or opinions of My Lovely Feline.

Common Cancers

Cancers can be grouped into two categories:

  1. Benign cancer doesn’t spread, so you can typically let a tumor be or remove it surgically.
  2. Regardless of where malignant cancers start, they can spread all over the body, causing internal organs not to function correctly and eventually leading to death.

Next, let’s look at the most common types of cancers.

  • Lymphoma - Lymphoma is caused by white blood cells, and by far the most common type cats get is in their intestines. It can start in their small or large intestine, stomach, spleen, or liver.
  • Squamous Cell Carcinoma - Squamous cells are skin cells, and cats can get it in their mouth, most commonly under their tongue. There isn’t a lot that can be done. Although the treatment is surgery to remove the tumors, there isn’t a lot of surface area to cut out because their mouths are so small.
  • Fibrocarma - These are usually associated with injections. Certain types of rabies vaccines could cause it in cats, although rare. We don’t know why, but for some reason, the cells under the skin can develop an overreaction, which causes a tumor. If a cat develops a growth or tumor, always get it checked.
  • Mammary Tumors - The chance of developing these can be drastically reduced if a cat is spayed before her first heat. About 90% of mammary cancers in cats are malignant and serious. The other 10% are localized to one mammary gland and don’t cause other issues.
  • There are other types of cancers, like basal cell carcinoma and mast cell tumors, but the ones above are the most common.

    Causes of Cancer in Cats

    Vets and scientists don’t know 100% of the time, but there are some diseases and conditions that come with an increased risk of cancer. These include:

    • Feline immunodeficiency virus (FIV)
    • Feline leukemia virus (FeLV)
    • Sex hormones
    • Any type of chronic inflammation, especially with conditions like chronic rhinitis (could lead to nasal or sinus tumors), allergies, and inflammatory bowel disease (IBD).

    Signs of Cancer in Cats

    It depends on the type of cancer.

    Mouth cancer:

    • Drooling
    • Difficulty eating
    • Bad breath or odor coming from the mouth
    • Bleeding in the mouth
    • Pawing at mouth
    • Decreased appetite


    • Weight loss
    • Decrease or increase in appetite
    • Pain
    • Lethargy
    • Vomiting
    • Diarrhea

    Some cancers can cause an increase in calcium, which increases urination. They’ll also be extra thirsty.

    Diagnosing Cancer in Cats

    Diagnosis can be very tricky. Bloodwork often doesn’t show cancer unless there is an elevated white blood cell count, low red blood cell count (anemia), or elevated calcium level. For cats, bloodwork is more required to rule out other types of diseases, like kidney disease, liver disease, elevated thyroid disease, and more.

    If it’s a tumor, a vet will most likely poke it with a needle and send what they extract to a lab. Sometimes cancer can be revealed, but other times, results are inconclusive. 

    The next step is a biopsy, where the cat is sedated and a piece of the tissue is sent to the lab for an official diagnosis. It could be a piece of the liver, spleen, or even intestines. The vet will either use a scope to get the sample or do exploratory surgery. 

    Ultrasound is also a way to help diagnose cancer. A vet may use a needle and take a sample while the cat is awake during the ultrasound. X-rays of the abdomen or chest can show tumors or signs of cancer too.

    Treatments for Cancer in Cats

    A cat can’t be treated for cancer without a confirmed diagnosis. Cancer treatment differs between types of cancer, and it can also be expensive.

    Veterinary medicines have expanded to treat cancer in pets, and there are many veterinary oncologists. Here are a few ways to treat cancer:

    • Surgery - Remove tumor and take clean margins to capture any cancerous cells so it can’t spread to other parts of the body.
    • Radiation - An expensive and time-consuming treatment, radiation requires a cat to go under general anesthesia and be placed into a machine where a radiation beam is directed at the tumor to make it smaller and kill some of the cells around it. 

    Sometimes, radiation is the first line of treatment to shrink the tumor so it can then be removed with surgery. If surgery isn’t an option, radiation may be recommended to slow down the growth and improve quality and length of life. It can also be used to manage pain.

    • Chemotherapy - Some chemo is injectable that the vet performs, and other forms are a pill that owners give the cat at home. You may have to wear gloves to handle the medication or when cleaning the litter box.
    • Steroids - Can improve the cat’s quality of life, slow down cancer growth, and control inflammation. 

    Long-term use isn’t a treatment option because often, the tumor becomes resistant to the steroid, but it can help in the short term.

    Treating cats with cancer is very different than treating people with cancer. 

    For instance, cats tolerate chemotherapy very well. The dosage given isn’t designed to extend their life, even though it does do that; the dose is to improve their quality of life.

    They don’t lose their fur, they don’t get nausea, vomiting, and lethargy to the same degree we see in people. You don’t have to worry about a cat feeling sick all the time. 

    Also, the dose can be adjusted if the cat starts to show any side effects. The limiting factor is more often cost and time dedication.

    The prognosis really depends on the type and stage of cancer, along with the treatment.


    Q: One of my cats had a hard time breathing, and they found fluid in her lungs. An ultrasound found lumps in the abdomen. I don’t remember if he told us if it was mammary or lymphoma. Our vet would take fluid out of her lungs every 2-3 months until she eventually declined. Is that something that happens with cancer? 

    Dr. Brooks: Yes, that can be a sign. I’m wondering if it was lymphoma that spread to her heart or her lungs. That would have caused the vessels in the lungs to become leaky and leak fluid into the lungs. Trouble breathing can definitely be a sign of certain types of cancer. 

    Customer: They’re so good at hiding it and acting fairly normal.

    Dr. Brooks: They definitely are, and if you see them every day and changes are minimal, symptoms are harder to notice. Cats can also get cancer in their spinal cord or brain. They’d need a CT or spinal tab to confirm that, and those can be risky procedures. It’s very hard to find and diagnose sometimes. Did the doctor ever conclude what it was?

    Customer: No. The cat came from outside and had conflicting feline leukemia tests, so we though she had it, but then she had a negative, and we didn’t know what to think. We also didn’t opt for treatment because we didn’t know radiation and chemo aren’t the same as in people, so I’m glad you talked about that.

    Dr. Brooks: They aren’t. In fact, I’d be more worried about side effects from radiation over chemo, but even radiation side effects aren’t that bad, because they try to really target the tumor. Regarding the test for feline leukemia, they still have issues with them. Last year, we tested a 5/6-month-old kitten and it was negative. Then we retested around a year because it was really sick and it was positive. The feline leukemia virus and the test itself are very frustrating.

    Liz: When my cat Vito had fibrosarcoma, he had five rounds of chemo. He was perfect through the first three, then mild symptoms after the last two. They really did a lot to keep him comfortable. He was on Cerenia, an anti-nausea medication. And there are other things they can do to make the symptoms not as bad. If anyone is ever faced with it, just talk to the oncologist ahead of time and get your questions answers. So if something comes up, you’ll know there are things to combat those side effects.

    Dr. Brooks: I agree. Also, cost is a huge factor. How many of you have pet insurance? It’s becoming more popular and I wish more pet owners took advantage of it.

    Liz: I know there are still deductibles too. It’s not like you get the insurance and never have to pay anything, but you’ll pay substantially less than you would without it.

    Customer: I have insurance through ASPCA and they covered 90% of my cat’s surgery.

    Liz: That’s amazing. I also want to mention that if you don’t have insurance, it’s likely going to be a couple of thousand dollars to treat your pet for cancer. You have to keep going back and they have to do bloodwork and X-rays to check their lungs. I’m just saying that so people think about it because it isn’t just treatment. They’ll space out the checkups eventually so it’s once a month, once every three months, then six months, and then once a year. It’s an added cost of a few hundred dollars every time you go for a checkup.

    Dr. Brooks: Liz, do you have any other experiences with pets with cancer?

    Liz: I do not. But I am familiar with nasal and oral cancers, unfortunately. In the two cases I knew, there was really nothing to be done. They weren’t my cats, but people I knew. It’s really sad to feel like there’s no real option. The one with the nasal tumor was a hospital kitty at a vet’s office, so you would think if anybody could do it, they could, but they couldn’t. Those are very frustrating I think because like you said, their noses and mouths are so tiny, there’s not a lot to take to remove anything. But I will say there are lots of different chemo options. 

    The most important thing I think is that you go to an oncologist for a consultation, and they’ll answer all your questions and review everything so that you know what you’re getting into financially, time-wise, and all of that. I’ve referred people to Vito’s oncologist and they were so relieved to have spoken with her, whether they decided to treat or not. That’s what they do all day and they know about new treatments and go to conferences in their specialty to get the most updated information. I would always get a consultation from an oncologist regardless of what your regular vet is saying.

    Dr. Brooks: I 100% agree. Not even just on cancer stuff, but with any condition where you can see a specialist. Just have a visit with the specialist, even if you end up not doing what they suggest. They might know newer things that I’m not aware of and they can give you percentages regarding the prognosis and life expectancy. They have access to the statistics on all of that.

    Liz: Totally agree. You’re a general practice vet and you know a ton, but might not know as much as what a specialist will know about what they deal with every day. Just like the specialist won’t know as much about general practice medicine as you do.

    Dr. Brooks: There might be trials and studies on different types of cancers, and a specialist is going to be aware of that over a general practice vet. And if you want to get into that trial, that could be free of charge. Usually, once there’s a trial, they’ve been seeing some improvement, so then you’re getting free cancer treatment for your pet.

    Liz: Another thing I want to bring up is that my cat Lucy has inflammatory bowel disease, but they misdiagnosed her ultrasound twice, and even though the scar tissues in her colon was actually a growth in her stomach. They said if there’s a growth in the stomach, it’s always cancerous. Just sharing that in case it comes up for anyone, if it’s in the stomach, it’s likely malignant.

    Q: We had a cat with a lot of respiratory issues, that stopped eating because he couldn’t smell, and our vet referred us to a teaching vet hospital, where he was diagnosed with cryptococcus. They had a new drug for us to try, and we had to work with them to figure out the best way to administer it. It took 30 days, but it did work, and he lived three more years. Could it still have been a nasal tumor?

    Dr. Brooks: No, if it worked, then it was cryptococcus.

    Liz: What is cryptococcus?

    Dr. Brooks: It’s a type of fungus. It would be treated differently than cancer because you wouldn’t treat a cat with a fungus with a drug that would suppress the immune system. Usually, if they have the tumor in the nasal cavity, they’ll have trouble breathing, and they’ll always be congested or have blood coming from their nose. So you were part of the study?

    Customer: Yes, we were really grateful. They diagnosed him by just keeping him overnight when we had been working with our vet for months.

    Dr. Brooks: I’m so glad you mentioned that if they can’t smell they won’t eat. We recommend feeding really stinky wet food to congested cats.

    Liz: I also steam up the bathroom and use nasal drops to help clear the nose. It usually helps the nose clear even temporarily to get them to start eating again.


    Cancer is a disease cats can get, and it’s hard to diagnose. It also knows no age, so even younger cats are at risk. There are treatments available, which can be expensive, and may or may not extend their life expectancy. If your vet diagnoses or suspects cancer in your pet, consult with a veterinary oncologist to learn about your options and the most up-to-date treatments. Measure the options, including cost and time commitment, and then decide what’s the best decision for you, your family, and your cat. 


    Call #15 Hosts:

    Dr. Leslie Brooks 👩‍⚕️

    Elizabeth Italia 🙋‍♀️
    Cat Behavior & Fostering Specialist

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